At what time

adverb

1. At what time

   "when will you return"

2. At or during which time
3. And then
4. At a former and usually less prosperous time

   "brag fondly of having known him when"

conjunction

1. At or during the time that while

   "went fishing when he was a boy"

2. Just at the moment that

   "stop writing when the bell rings"

3. At any or every time that

   "when he listens to music, he falls asleep"

4. In the event that if

   "a contestant is disqualified when he disobeys the rules"

5. Considering that

   "why use water at all when you can drown in it"

6. In spite of the fact that although

   "quit politics when I might have had a great career in it"

7. The time or occasion at or in which

   "tomorrow is when we must decide"

pronoun

1. What or which time

   "life-long homes for those … who have lived here since when"

noun

1. The time in which something is done or comes about

   "troubled his head very little about the hows and whens of life"

idiom

1. After considering or doing everything

idiom

1. Used to say that one thinks that something will never happen

idiom

1. When really necessary or important

   "When it comes down to it, he can be generous."

idiom

1. Used to identify the specific topic that is being talked about

idiom

1. Used to say that when something bad happens other bad things usually happen at the same time

idiom

1. When a person gets the chance to do something he or she wants to do

   "You need to be ready when opportunity knocks."