when >> wɛn
Definition: [adverb] at what time.
Example: when did you last see him?
Definition: [adverb] at or on which (referring to a time or circumstance).
Example: Saturday is the day when I get my hair done
Definition: [conjunction] at or during the time that.
Example: I loved maths when I was at school
Definition: [conjunction] after which; and just then (implying suddenness).
Example: he had just drifted off to sleep when the phone rang
Definition: [conjunction] in view of the fact that; considering that.
Example: why bother to paint it when you can photograph it with the same effect?
Definition: [conjunction] although; whereas.
Example: I'm saying it now when I should have told you long ago