To speak to someone in private.

(idiomatic) Thoroughly; including every detail; with all particulars. / (military) By engaging small sections of an enemy army rather than fighting a single pitched battle against the entire enemy force.

plural of diamond in the rough

to an extent; not fully.

(intransitive, slang, idiomatic) To kick a fallen opponent. / (intransitive, slang, figuratively) To kick someone when they are down.

One should not attempt to take on more than one can handle.

According to one's subjectively formed thoughts, not necessarily having any formal basis in fact.

A course of action doomed to be futile.

plural of exercise in futility

(idiomatic) used to add emphasis to "why" when beginning question.