adv at what time;
used interrogatively.
2. when ·adv which time; then;
used elliptically as a noun.
3. when ·adv at what time; at, during, or after the time that; at or just after, the moment that;
used relatively.
4. when ·adv while; whereas; although;
used in the manner of a conjunction to introduce a dependent adverbial sentence or clause, having a causal, conditional, or adversative relation to the principal proposition; as, he chose to turn highwayman when he might have continued an honest man; he removed the tree when it was the best in the grounds.