Definition of "let down"

let down

verb
third-person singular simple present lets down, present participle letting down, simple past and past participle let down
1. Used other than figuratively or idiomatically: see let,‎ down.
2. (transitive) To allow to descend.
3. (transitive, idiomatic) To disappoint; to betray or fail somebody
  Quotations
  Just as they left, the younger of the two turned around and said, "Mr. President, I just want you to know that we're praying for you," and quickly closed the door behind him.I thought about these two men, and about the office workers that afternoon, and about the millions of others like them all across the country who still had faith in me. I knew that by resigning I would let them down.
  1978, Richard Nixon, “The Presidency 1973-1974”, in RN: the Memoirs of Richard Nixon‎, Grosset & Dunlap, page 1065
  Sooner or later / You hit the deck, you get found out / Save it for later / Don't run away and let me down
  1982, The English Beat (lyrics and music), “Save It for Later”, in Special Beat Service
  ASLEF General Secretary Mick Whelan said: "AWC has continued to cancel services and, every day, continued to let passengers down. But the Government doesn't seem to care.
  2023 April 5, “Network News: Conservatives accused of "rewarding Avanti's failure"”, in RAIL, number 980, page 6
4. (transitive, of clothing) To lengthen by undoing and resewing a hem.
5. (intransitive) To reduce one's level of effort.
6. To soften in tempering.