1
general::
Phrase(s): let someone down
to disappoint someone; to fail someone. • I’m sorry I let you down. Something came up, and I couldn’t meet you. • I don’t want to let you down, but I can’t support you in the election., Phrase(s): let someone or something down
Fig. to fail someone or something; to disappoint someone or a group. • Please don’t let me down. I am depending on you. • I let down the entire cast of the play., Phrase(s): let down
to relax one’s efforts or vigilance. • Now is no time to let down. Keep on your guard. • After the contest was over, Jane let down a bit so she could relax.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
1. Cause to descend, lower, as in They let down the sails. [Mid-1100s] 2. Also, let up. Slacken, abate, as in Sales are letting down in this quarter, or They didn't let up in their efforts until the end. The first term dates from the mid-1800s, the variant from the late 1700s. 3. See LET SOMEONE DOWN. Also see LET ONE'S HAIR DOWN.
American Heritage Idioms