let

from The American Heritage® Dictionary of the English Language, 5th Edition.

• intransitive verb To give permission or opportunity to; allow.
• intransitive verb To cause to; make.
• intransitive verb Used as an auxiliary in the imperative to express a command, request, or proposal.
• intransitive verb Used as an auxiliary in the imperative to express a warning or threat.
• intransitive verb To permit to enter, proceed, or depart.
• intransitive verb To release from or as if from confinement.
• intransitive verb To rent or lease.
• intransitive verb To award, especially after bids have been submitted.
• intransitive verb To become rented or leased.
• intransitive verb To be or become assigned, as to a contractor.
• idiom (let alone) Not to mention; much less.
• idiom (let go) To cease to employ; dismiss.
• idiom (let off on) To cause to diminish, as in pressure; ease up on.
• idiom (let (one's) hair down) To drop one's reserve or inhibitions.
• idiom (let (someone) have it) To beat, strike, or shoot at someone.
• idiom (let (someone) have it) To scold or punish.
• idiom (let (someone) in on) To reveal (a secret) to someone.
• idiom (let (someone) in on) To allow someone to participate in (something).
• idiom (let up on) To be or become more lenient with.
• noun Something that hinders; an obstacle.
• noun Sports An invalid stroke in tennis and other net games that requires a replay.
• transitive verb To hinder or obstruct.

from The Century Dictionary.

• To delay; retard; hinder; prevent; stop.
• To delay; hesitate; waver; be slow.
• To forbear; cease; leave off.
• To be a hindrance; stand in the way.
• noun A letting for hire or rent.
• noun A retarding; hindrance; obstacle; impediment; delay: now currently used only in the tautological phrase “without let or hindrance.”
• In cricket, to miss a chance of catching (a hatsman) out.
• noun A diminutive suffix, as in bracelet, hamlet, rivulet, etc., and other words from or based upon the French.
• noun In lawn-tennis, hand-tennis, and other games played with a net, a service-ball which strikes the top of the net and then goes into the proper court; also, any unforeseen or accidental hindrance of a like nature which the umpire may on appeal so designate.
• noun Abbreviations of Lettish.
• To permit or allow (to be or to do), either actively or passively; grant or afford liberty (to): followed by an infinitive without to: as, to let one do as he pleases; to let slip an opportunity.
• Hence also much used as a kind of imperative auxiliary, with following infinitive, to form imperative first and third persons: as, let him be accursed (literally, allow him to be accursed); let them retire at once; let us pray; let me be listened to when I speak.
• To furnish with leave or ability by direct action or agency; enable, cause, or make to do or to be: followed by an infinitive without to (except in the passive), or by a definitive adjective or adverb (with ellipsis of go, come, or get before the adverb): as, I will let you know my decision; let me understand your claim; to let a person in (come in or enter); to let a man out of prison.
• To leave; allow to remain or abide; suffer to continue or proceed.
• To leave the care or control of; commit or intrust; resign; relinquish; leave.
• To leave or transfer the use of for a consideration; put to rent or hire; farm; lease: often with out: as, to let a house to a tenant; to let out boats or carriages for hire.
• To cause: with an infinitive, without to, in a quasi-passive use (the original subject of the infinitive being omitted): as, to let make (cause to be made); to let call (cause to be called). It is sometimes joined with do, without change of meaning.