—v.t. 1. to make use of as relevant, suitable, or pertinent: to apply a theory to a problem. 2. to put to use, esp. for a particular purpose: to apply pressure to open a door. 3. to bring into action; use; employ: He applied the brakes and skidded to a stop. 4. to use a label or other designation: Don't apply any such term to me. 5. to use for or assign to a specific purpose: He applied a portion of his salary each week to savings. 6. to put into effect: They applied the rules to new members only. 7. to devote or employ diligently or with close attention: to apply one's mind to a problem; to apply oneself to a task. 8. to place in contact with; lay or spread on: to apply paint to a wall; to apply a bandage to a wound. 9. to bring into physical contact with or close proximity to: to apply a match to gunpowder. 10. to credit to, as an account: to apply $10 to his account at the store.
—v.i. 1. to be pertinent, suitable, or relevant: The argument applies to the case. The theory doesn't apply. 2. to make an application or request; ask: to apply for a job; to apply for a raise. 3. to lay or spread on: The plastic coating is easy to apply on any surface. 4. to be placed or remain in contact: This paint doesn't apply very easily.