(uncommon) Alternative form of when in Rome, do as the Romans do

(idiomatic, simile, chiefly hyperbolic) Extremely old.

(simile) extremely light, having minimal weight

(simile, colloquial) Unquestionably guilty.

(chiefly UK and Ireland, idiomatic, vulgar, simile) Extremely happy; obviously satisfied and carefree.

(simile) Extremely easy

Just the right amount is as good as more than enough: there is no value in excess.

In the role or manner of the thing mentioned. / (usually in negative constructions) In a true or literal sense. / Per se, by itself, in itself, in and of itself.

(idiomatic) To behave toward others in a manner resembling or commensurate with their behavior towards oneself, especially in a situation where one is insulted or otherwise ill-treated.

(idiomatic) Used to express reluctance, to express that if one hypothetical or possible action happened, it would not make any notable difference