(often humorous) Even if a person is in his or her senior years, with gray hair, he or she can still have ambition and energy, especially sexual energy.

A block copolymer consisting of two polystyrene chains, one each side of a polybutadiene sequence; they have both thermoset and thermoplastic properties.

(rhetorical question, colloquial, childish) Assertion that an insult made by the party to whom the phrase is directed is actually true of that party, and not of the person using the phrase. Usually considered to be a playground taunt.

(organic chemistry) diacetylene

(organic chemistry) The univalent radical HC≡C-C≡C- derived from butadiyne

(academics) A status of a doctoral student who has completed all PhD degree requirements except the doctoral dissertation.

History (or progress) moves ahead, no matter the criticism it may attract.

Used to cut off objections or qualifications.

plural of butadiynyl

(organic chemistry) Denotes the presence of four carbon atoms in the parent chain when forming names of organic compounds.