not expounded, simple

(chemistry, physics) an atomic or molecular orbital whose energy increases as its constituent atoms are brought closer together - thus generating a repulsive force that hinders bonding

(chemistry) An explosive nitro derivative of certain sugars, analogous to nitroglycerin, guncotton, etc.

(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′).