If you want to buy this dictionary, don't buy the 4th edition. There is a newer edition (currently the 5th edition is the newest edition). The 4th edition is not comprehensive enough and leaves out these terms: • arity • class (of x), written as [x] • commutativity (of maps) • determinant (from the quadratic formula: b^2-4ac) • endomorphism • functor • idempotent • kernel / null space (but 'nullity' is defined) • kernel equivalence • level curve/surface (f(x, y, z) = a constant) • magma/groupoid • monoid • monomorphism • nabla (although 'gradient (grad)' is defined as the vector obtained by applying the del operator) • natural map / canonical map (π : X→X/E) • similar matrices (If Q^(-1) A Q = B then A and B are similar) • simply-connected region • standard basis (although the equivalent term 'canonical basis' is included) • standard product • uniform convergence