1. To give permission or opportunity to; allow: I let them borrow the car. The inheritance let us finally buy a house. See Usage Note at leave1.
2. To cause to; make: Let the news be known.
3.
a. Used as an auxiliary in the imperative to express a command, request, or proposal: Let's finish the job! Let x equal y.
b. Used as an auxiliary in the imperative to express a warning or threat: Just let her try!
4. To permit to enter, proceed, or depart: let the dog in.
5. To release from or as if from confinement: let the air out of the balloon; let out a yelp.
6. To rent or lease: let rooms.
7. To award, especially after bids have been submitted: let the construction job to a new firm.