diff --git a/base/linalg/bidiag.jl b/base/linalg/bidiag.jl
index 8701c11b8bdf5..bf8fd97418af7 100644
--- a/base/linalg/bidiag.jl
+++ b/base/linalg/bidiag.jl
@@ -114,7 +114,7 @@ end
 /(A::Bidiagonal, B::Number) = Bidiagonal(A.dv/B, A.ev/B, A.isupper)
 ==(A::Bidiagonal, B::Bidiagonal) = (A.dv==B.dv) && (A.ev==B.ev) && (A.isupper==B.isupper)
 
-SpecialMatrix = Union(Diagonal, Bidiagonal, SymTridiagonal, Tridiagonal, TriangularUnion)
+SpecialMatrix = Union(Diagonal, Bidiagonal, SymTridiagonal, Tridiagonal, AbstractTriangular)
 *(A::SpecialMatrix, B::SpecialMatrix)=full(A)*full(B)
 
 #Generic multiplication
@@ -126,11 +126,11 @@ end
 
 
 #Linear solvers
-A_ldiv_B!(A::Union(Bidiagonal, TriangularUnion), b::AbstractVector) = naivesub!(A, b)
-At_ldiv_B!(A::Union(Bidiagonal, TriangularUnion), b::AbstractVector) = naivesub!(transpose(A), b)
-Ac_ldiv_B!(A::Union(Bidiagonal, TriangularUnion), b::AbstractVector) = naivesub!(ctranspose(A), b)
+A_ldiv_B!(A::Union(Bidiagonal, AbstractTriangular), b::AbstractVector) = naivesub!(A, b)
+At_ldiv_B!(A::Union(Bidiagonal, AbstractTriangular), b::AbstractVector) = naivesub!(transpose(A), b)
+Ac_ldiv_B!(A::Union(Bidiagonal, AbstractTriangular), b::AbstractVector) = naivesub!(ctranspose(A), b)
 for func in (:A_ldiv_B!, :Ac_ldiv_B!, :At_ldiv_B!) @eval begin
-    function ($func)(A::Union(Bidiagonal, TriangularUnion), B::AbstractMatrix)
+    function ($func)(A::Union(Bidiagonal, AbstractTriangular), B::AbstractMatrix)
         tmp = similar(B[:,1])
         n = size(B, 1)
         for i = 1:size(B,2)
@@ -142,7 +142,7 @@ for func in (:A_ldiv_B!, :Ac_ldiv_B!, :At_ldiv_B!) @eval begin
     end
 end end
 for func in (:A_ldiv_Bt!, :Ac_ldiv_Bt!, :At_ldiv_Bt!) @eval begin
-    function ($func)(A::Union(Bidiagonal, TriangularUnion), B::AbstractMatrix)
+    function ($func)(A::Union(Bidiagonal, AbstractTriangular), B::AbstractMatrix)
         tmp = similar(B[:, 2])
         m, n = size(B)
         nm = n*m
diff --git a/base/linalg/factorization.jl b/base/linalg/factorization.jl
index dbf80951b8a08..deb3981ac8655 100644
--- a/base/linalg/factorization.jl
+++ b/base/linalg/factorization.jl
@@ -274,7 +274,7 @@ function A_mul_Bc!{T}(A::AbstractMatrix{T},Q::QRPackedQ{T})
     end
     A
 end
-A_mul_Bc(A::TriangularUnion, B::Union(QRCompactWYQ,QRPackedQ)) = A_mul_Bc(full(A), B)
+A_mul_Bc(A::AbstractTriangular, B::Union(QRCompactWYQ,QRPackedQ)) = A_mul_Bc(full(A), B)
 function A_mul_Bc{TA,TB}(A::AbstractArray{TA}, B::Union(QRCompactWYQ{TB},QRPackedQ{TB}))
     TAB = promote_type(TA,TB)
     A_mul_Bc!(size(A,2)==size(B.factors,1) ? (TA == TAB ? copy(A) : convert(AbstractMatrix{TAB}, A)) :
diff --git a/base/linalg/generic.jl b/base/linalg/generic.jl
index 861d101afe83b..b54f4d9db6411 100644
--- a/base/linalg/generic.jl
+++ b/base/linalg/generic.jl
@@ -1,9 +1,5 @@
 ## linalg.jl: Some generic Linear Algebra definitions
 
-# Fall back arithmetic
-+(A::AbstractMatrix, B::AbstractMatrix) = full(A) + full(B)
--(A::AbstractMatrix, B::AbstractMatrix) = full(A) - full(B)
-
 scale(X::AbstractArray, s::Number) = scale!(copy(X), s)
 scale(s::Number, X::AbstractArray) = scale!(copy(X), s)
 
diff --git a/base/linalg/sparse.jl b/base/linalg/sparse.jl
index d507bbb8e6a53..08a72a0f9b81e 100644
--- a/base/linalg/sparse.jl
+++ b/base/linalg/sparse.jl
@@ -126,7 +126,7 @@ end
 *{TvA,TiA}(X::BitArray{2}, A::SparseMatrixCSC{TvA,TiA}) = invoke(*, (AbstractMatrix, SparseMatrixCSC), X, A)
 # TODO: Tridiagonal * Sparse should be implemented more efficiently
 *{TX,TvA,TiA}(X::Tridiagonal{TX}, A::SparseMatrixCSC{TvA,TiA}) = invoke(*, (Tridiagonal, AbstractMatrix), X, A)
-*{TvA,TiA}(X::TriangularUnion, A::SparseMatrixCSC{TvA,TiA}) = full(X)*A
+*{TvA,TiA}(X::AbstractTriangular, A::SparseMatrixCSC{TvA,TiA}) = full(X)*A
 function *{TX,TvA,TiA}(X::AbstractMatrix{TX}, A::SparseMatrixCSC{TvA,TiA})
     mX, nX = size(X)
     nX == A.m || throw(DimensionMismatch())
diff --git a/base/linalg/special.jl b/base/linalg/special.jl
index 0c0af842fe4c0..0961652c7f8f1 100644
--- a/base/linalg/special.jl
+++ b/base/linalg/special.jl
@@ -46,12 +46,12 @@ function convert(::Type{SymTridiagonal}, A::Tridiagonal)
     SymTridiagonal(A.d, A.dl)
 end
 
-function convert(::Type{Diagonal}, A::TriangularUnion)
+function convert(::Type{Diagonal}, A::AbstractTriangular)
     full(A) == diagm(diag(A)) || throw(ArgumentError("Matrix cannot be represented as Diagonal"))
     Diagonal(diag(A))
 end
 
-function convert(::Type{Bidiagonal}, A::TriangularUnion)
+function convert(::Type{Bidiagonal}, A::AbstractTriangular)
     fA = full(A)
     if fA == diagm(diag(A)) + diagm(diag(fA, 1), 1)
         return Bidiagonal(diag(A), diag(fA,1), true)
@@ -62,9 +62,9 @@ function convert(::Type{Bidiagonal}, A::TriangularUnion)
     end
 end
 
-convert(::Type{SymTridiagonal}, A::TriangularUnion) = convert(SymTridiagonal, convert(Tridiagonal, A))
+convert(::Type{SymTridiagonal}, A::AbstractTriangular) = convert(SymTridiagonal, convert(Tridiagonal, A))
 
-function convert(::Type{Tridiagonal}, A::TriangularUnion)
+function convert(::Type{Tridiagonal}, A::AbstractTriangular)
     fA = full(A)
     if fA == diagm(diag(A)) + diagm(diag(fA, 1), 1) + diagm(diag(fA, -1), -1)
         return Tridiagonal(diag(fA, -1), diag(A), diag(fA,1))
@@ -115,7 +115,7 @@ for op in (:+, :-)
     end
 end
 
-A_mul_Bc!(A::TriangularUnion, B::QRCompactWYQ) = A_mul_Bc!(full!(A),B)
-A_mul_Bc!(A::TriangularUnion, B::QRPackedQ) = A_mul_Bc!(full!(A),B)
-A_mul_Bc(A::TriangularUnion, B::Union(QRCompactWYQ,QRPackedQ)) = A_mul_Bc(full(A), B)
+A_mul_Bc!(A::AbstractTriangular, B::QRCompactWYQ) = A_mul_Bc!(full!(A),B)
+A_mul_Bc!(A::AbstractTriangular, B::QRPackedQ) = A_mul_Bc!(full!(A),B)
+A_mul_Bc(A::AbstractTriangular, B::Union(QRCompactWYQ,QRPackedQ)) = A_mul_Bc(full(A), B)
 
diff --git a/base/linalg/triangular.jl b/base/linalg/triangular.jl
index 2ec3bb7881da7..086dacc1da353 100644
--- a/base/linalg/triangular.jl
+++ b/base/linalg/triangular.jl
@@ -1,9 +1,11 @@
 ## Triangular
 
+abstract AbstractTriangular{T,S<:AbstractMatrix} <: AbstractMatrix{T} # could be renamed to Triangular when than name has been fully deprecated
+
 # First loop through all methods that don't need special care for upper/lower and unit diagonal
 for t in (:LowerTriangular, :UnitLowerTriangular, :UpperTriangular, :UnitUpperTriangular)
     @eval begin
-        immutable $t{T,S<:AbstractMatrix} <: AbstractMatrix{T}
+        immutable $t{T,S<:AbstractMatrix} <: AbstractTriangular{T,S}
             data::S
         end
         function $t(A::AbstractMatrix)
@@ -35,12 +37,9 @@ for t in (:LowerTriangular, :UnitLowerTriangular, :UpperTriangular, :UnitUpperTr
     end
 end
 
-# some cases can be handled with a union
-typealias TriangularUnion{T,S} Union(UpperTriangular{T,S}, UnitUpperTriangular{T,S}, LowerTriangular{T,S}, UnitLowerTriangular{T,S})
-
-full{T,S}(A::TriangularUnion{T,S}) = convert(Matrix, A)
+full(A::AbstractTriangular) = convert(Matrix, A)
 
-fill!(A::TriangularUnion, x) = (fill!(A.data, x); A)
+fill!(A::AbstractTriangular, x) = (fill!(A.data, x); A)
 
 # then handle all methods that requires specific handling of upper/lower and unit diagonal
 
@@ -102,7 +101,7 @@ function full!{T,S}(A::UnitUpperTriangular{T,S})
     B
 end
 
-getindex(A::TriangularUnion, i::Integer) = ((m, n) = divrem(i - 1, size(A, 1)); A[n + 1, m + 1])
+getindex(A::AbstractTriangular, i::Integer) = ((m, n) = divrem(i - 1, size(A, 1)); A[n + 1, m + 1])
 getindex{T,S}(A::UnitLowerTriangular{T,S}, i::Integer, j::Integer) = i == j ? one(T) : (i > j ? A.data[i,j] : zero(A.data[i,j]))
 getindex{T,S}(A::LowerTriangular{T,S}, i::Integer, j::Integer) = i >= j ? A.data[i,j] : zero(A.data[i,j])
 getindex{T,S}(A::UnitUpperTriangular{T,S}, i::Integer, j::Integer) = i == j ? one(T) : (i < j ? A.data[i,j] : zero(A.data[i,j]))
@@ -172,6 +171,7 @@ end
 +(A::UnitLowerTriangular, B::LowerTriangular) = LowerTriangular(tril(A.data, -1) + B.data + I)
 +(A::UnitUpperTriangular, B::UnitUpperTriangular) = UpperTriangular(triu(A.data, 1) + triu(B.data, 1) + 2I)
 +(A::UnitLowerTriangular, B::UnitLowerTriangular) = LowerTriangular(tril(A.data, -1) + tril(B.data, -1) + 2I)
++(A::AbstractTriangular, B::AbstractTriangular) = full(A) + full(B)
 
 -(A::UpperTriangular, B::UpperTriangular) = UpperTriangular(A.data - B.data)
 -(A::LowerTriangular, B::LowerTriangular) = LowerTriangular(A.data - B.data)
@@ -181,14 +181,15 @@ end
 -(A::UnitLowerTriangular, B::LowerTriangular) = LowerTriangular(tril(A.data, -1) - B.data + I)
 -(A::UnitUpperTriangular, B::UnitUpperTriangular) = UpperTriangular(triu(A.data, 1) - triu(B.data, 1))
 -(A::UnitLowerTriangular, B::UnitLowerTriangular) = LowerTriangular(tril(A.data, -1) - tril(B.data, -1))
+-(A::AbstractTriangular, B::AbstractTriangular) = full(A) - full(B)
 
 ######################
 # BlasFloat routines #
 ######################
 
-A_mul_B!(A::Tridiagonal, B::TriangularUnion) = A*full!(B)
-A_mul_B!(C::AbstractVecOrMat, A::TriangularUnion, B::AbstractVecOrMat) = A_mul_B!(A, copy!(C, B))
-A_mul_Bc!(C::AbstractVecOrMat, A::TriangularUnion, B::AbstractVecOrMat) = A_mul_Bc!(A, copy!(C, B))
+A_mul_B!(A::Tridiagonal, B::AbstractTriangular) = A*full!(B)
+A_mul_B!(C::AbstractVecOrMat, A::AbstractTriangular, B::AbstractVecOrMat) = A_mul_B!(A, copy!(C, B))
+A_mul_Bc!(C::AbstractVecOrMat, A::AbstractTriangular, B::AbstractVecOrMat) = A_mul_Bc!(A, copy!(C, B))
 
 for (t, uploc, isunitc) in ((:LowerTriangular, 'L', 'N'),
                             (:UnitLowerTriangular, 'L', 'U'),
@@ -238,8 +239,8 @@ for (t, uploc, isunitc) in ((:LowerTriangular, 'L', 'N'),
     end
 end
 
-errorbounds{T<:Union(BigFloat, Complex{BigFloat}),S<:StridedMatrix}(A::TriangularUnion{T,S}, X::StridedVecOrMat{T}, B::StridedVecOrMat{T}) = error("not implemented yet! Please submit a pull request.")
-function errorbounds{TA<:Number,S<:StridedMatrix,TX<:Number,TB<:Number}(A::TriangularUnion{TA,S}, X::StridedVecOrMat{TX}, B::StridedVecOrMat{TB})
+errorbounds{T<:Union(BigFloat, Complex{BigFloat}),S<:StridedMatrix}(A::AbstractTriangular{T,S}, X::StridedVecOrMat{T}, B::StridedVecOrMat{T}) = error("not implemented yet! Please submit a pull request.")
+function errorbounds{TA<:Number,S<:StridedMatrix,TX<:Number,TB<:Number}(A::AbstractTriangular{TA,S}, X::StridedVecOrMat{TX}, B::StridedVecOrMat{TB})
     TAXB = promote_type(TA, TB, TX, Float32)
     errorbounds(convert(AbstractMatrix{TAXB}, A), convert(AbstractArray{TAXB}, X), convert(AbstractArray{TAXB}, B))
 end
@@ -733,12 +734,12 @@ end
 
 for f in (:*, :Ac_mul_B, :At_mul_B, :A_mul_Bc, :A_mul_Bt, :Ac_mul_Bc, :At_mul_Bt, :\, :Ac_ldiv_B, :At_ldiv_B)
     @eval begin
-        ($f)(A::TriangularUnion, B::TriangularUnion) = ($f)(A, full(B))
+        ($f)(A::AbstractTriangular, B::AbstractTriangular) = ($f)(A, full(B))
     end
 end
 for f in (:A_mul_Bc, :A_mul_Bt, :Ac_mul_Bc, :At_mul_Bt, :/, :A_rdiv_Bc, :A_rdiv_Bt)
     @eval begin
-        ($f)(A::TriangularUnion, B::TriangularUnion) = ($f)(full(A), B)
+        ($f)(A::AbstractTriangular, B::AbstractTriangular) = ($f)(full(A), B)
     end
 end
 
@@ -746,7 +747,7 @@ end
 ### Multiplication with triangle to the left and hence rhs cannot be transposed.
 for (f, g) in ((:*, :A_mul_B!), (:Ac_mul_B, :Ac_mul_B!), (:At_mul_B, :At_mul_B!))
     @eval begin
-        function ($f){TA,TB}(A::TriangularUnion{TA}, B::StridedVecOrMat{TB})
+        function ($f){TA,TB}(A::AbstractTriangular{TA}, B::StridedVecOrMat{TB})
             TAB = typeof(zero(TA)*zero(TB) + zero(TA)*zero(TB))
             ($g)(TA == TAB ? copy(A) : convert(AbstractArray{TAB}, A), TB == TAB ? copy(B) : convert(AbstractArray{TAB}, B))
         end
@@ -789,7 +790,7 @@ end
 ### Multiplication with triangle to the rigth and hence lhs cannot be transposed.
 for (f, g) in ((:*, :A_mul_B!), (:A_mul_Bc, :A_mul_Bc!), (:A_mul_Bt, :A_mul_Bt!))
     @eval begin
-        function ($f){TA,TB}(A::StridedVecOrMat{TA}, B::TriangularUnion{TB})
+        function ($f){TA,TB}(A::StridedVecOrMat{TA}, B::AbstractTriangular{TB})
             TAB = typeof(zero(TA)*zero(TB) + zero(TA)*zero(TB))
             ($g)(TA == TAB ? copy(A) : convert(AbstractArray{TAB}, A), TB == TAB ? copy(B) : convert(AbstractArray{TAB}, B))
         end
@@ -866,8 +867,8 @@ sqrtm(A::LowerTriangular) = sqrtm(A.').'
 sqrtm(A::UnitLowerTriangular) = sqrtm(A.').'
 
 #Generic eigensystems
-eigvals(A::TriangularUnion) = diag(A)
-function eigvecs{T}(A::TriangularUnion{T})
+eigvals(A::AbstractTriangular) = diag(A)
+function eigvecs{T}(A::AbstractTriangular{T})
     TT = promote_type(T, Float32)
     TT <: BlasFloat && return eigvecs(convert(AbstractMatrix{TT}, A))
     error("type not handled yet. Please submit a pull request.")
@@ -877,14 +878,14 @@ det{T}(A::UnitLowerTriangular{T}) = one(T)*one(T)
 det{T}(A::UpperTriangular{T}) = prod(diag(A.data))
 det{T}(A::LowerTriangular{T}) = prod(diag(A.data))
 
-eigfact(A::TriangularUnion) = Eigen(eigvals(A), eigvecs(A))
+eigfact(A::AbstractTriangular) = Eigen(eigvals(A), eigvecs(A))
 
 #Generic singular systems
 for func in (:svd, :svdfact, :svdfact!, :svdvals)
     @eval begin
-        ($func)(A::TriangularUnion) = ($func)(full(A))
+        ($func)(A::AbstractTriangular) = ($func)(full(A))
     end
 end
 
-factorize(A::TriangularUnion) = A
+factorize(A::AbstractTriangular) = A
 
diff --git a/base/linalg/uniformscaling.jl b/base/linalg/uniformscaling.jl
index 4bf9627540511..9815a93bf2f23 100644
--- a/base/linalg/uniformscaling.jl
+++ b/base/linalg/uniformscaling.jl
@@ -84,7 +84,7 @@ inv(J::UniformScaling) = UniformScaling(inv(J.λ))
 /(J::UniformScaling, x::Number) = UniformScaling(J.λ/x)
 
 \(J1::UniformScaling, J2::UniformScaling) = J1.λ == 0 ? throw(SingularException(1)) : UniformScaling(J1.λ\J2.λ)
-\{T<:Number}(A::Union(Bidiagonal{T},TriangularUnion{T}), J::UniformScaling) = inv(A)*J.λ
+\{T<:Number}(A::Union(Bidiagonal{T},AbstractTriangular{T}), J::UniformScaling) = inv(A)*J.λ
 \(J::UniformScaling, A::AbstractVecOrMat) = J.λ == 0 ? throw(SingularException(1)) : J.λ\A
 \(A::AbstractMatrix, J::UniformScaling) = inv(A)*J.λ