What is the meaning of When?

At what time? At which time? Upon which occasion or circumstance? Used to introduce direct or indirect questions about time.

Used after a noun or noun phrase in isolation to express impatience with an anticipated future event.

At an earlier time and under different, usually less favorable, circumstances.

At which, on which, during which: often omitted or replaced with that.

The time at, on or during which.

A circumstance or situation in which.

At (or as soon as) that time that; at the (or any and every) time that; if.

During the time that; at the time of the action of the following clause or participle phrase.

At what time; at which time.

Since; given the fact that; considering that.

Whereas; although; at the same time as; in spite of the fact that.

What time; which time.

The time at which something happens.

That's enough: a command asking someone to stop adding something, especially an ingredient or portion of food or drink; used in, or as if in, literal response to 'Say when'.

Expressing impatience.

Alternative form of whenne

Alternative form of whenne

Alternative form of winnen (to win)

Source: wiktionary.org