Noun
(mathematics) Formally, given two partially ordered sets A and B, the order ≤ on the Cartesian product A × B such that (a,b) ≤ (a′,b′) if and only if a < a′ or (a = a′ and b ≤ b′).
(mathematics) Given sets (A1, A2, ..., An) and their total orderings (<1, <2, ..., Close letter words and terms