(idiomatic, nautical) About to be married.

Alternative spelling of on demand

(idiomatic) Honest(ly), sincere(ly), straightforward(ly), fair(ly). / Synonym of on the square (“discreet reference to freemasonry”)

(US, idiomatic) After reconsidering; on further consideration.

(idiomatic) On one's hands and knees. / (idiomatic, often followed by "with") In a manner which is similar in nature or effect to something else; consistently.

(idiomatic) Tense, nervous; consequently irritable.

Alternative form of in heat

(colloquial, politics) Alternative spelling of on-message

(idiomatic) Unwillingly agreed to or barely tolerated.

(informal) Economically, especially if too economically.