(intransitive) To lay down a challenge; to provide a test of commitment (often one which carries a high risk) to a cause.

(idiomatic) After a very long time; eventually; over a long period of time; more generally.

All possible knowledge of a subject matter. / All possible means, both honest and dishonest

As an exchange or replacement. / To reciprocate.

plural of niece-in-law

A grandfather of one's spouse.

present participle of opt in

(humorous, euphemistic) Lacking in intelligence; dimwitted.

(transitive) to fill in or write in using pencil / (idiomatic, transitive) to provisionally schedule

plural of thief in the night