What's the difference between once and when?

Once


Definition:

  • (adv.) By limitation to the number one; for one time; not twice nor any number of times more than one.
  • (adv.) At some one period of time; -- used indefinitely.
  • (adv.) At any one time; -- often nearly equivalent to ever, if ever, or whenever; as, once kindled, it may not be quenched.

Example Sentences:

When


Definition:

  • (adv.) At what time; -- used interrogatively.
  • (adv.) At what time; at, during, or after the time that; at or just after, the moment that; -- used relatively.
  • (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.
  • (adv.) Which time; then; -- used elliptically as a noun.

Example Sentences: