When

·adv At what time;

— used interrogatively.

II. When ·adv Which time; then;

— used elliptically as a noun.

III. When ·adv At what time; at, during, or after the time that; at or just after, the moment that;

— used relatively.

IV. 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.