When meaning : The time at which something happens. (interrogative) At what time? At which time? Upon which occasion or circumstance? Used to introduce direct or indirect questions about time. At an earlier time and under different, usually less favorable, circumstances. (relative) At which, on which, during which: often omitted or replaced with that. (interrogative) What time; which time. The time that. 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. That's enough, a command to stop adding something, especially an ingredient of food or drink. Expressing impatience. (Compare what.)