To let somebody down is to disappoint them when they were counting on you. The failure is in the relying.
That is what makes it worse than merely disappointing somebody, since letting down implies a promise or an expectation you had accepted. It splits round an object. There is a plain physical sense too, since letting down a tyre releases the air and letting down a hem lengthens a garment. The noun a let-down means a disappointment, usually after something had been built up.
Practised in Phrasal Verbs, A Man Called Ove
First appears in chapter 22 of A Man Called Ove.
Practise this word