(poker) Ace-high straight flush; a hand consisting of the cards A, K, Q, J, 10, of the same suit. This is the rarest and strongest hand in poker.

(aviation) Initialism of first officer. / (military, aviation) Abbreviation of flying officer.

(biochemistry) A dipeptide consisting of two leucine molecules joined via a peptide bond.

(biochemistry) Pertaining to hormones. / (colloquial) Of or pertaining to the menstrual cycle. / Strongly affected by one's hormones.