A grammatical question

[rado84]

I don't have access right now to some of the sites I usually use for information about expressions, so I have to ask you all: Is there any difference between the expressions "turn someone down" and "let someone down"? And if yes, what is it? I know that the second one means "to disappoint someone" but I'm not sure what the first one means.

[FatAndFaithless]

To 'turn someone down' usually means to deny or decline a request from them, where as 'letting someone down' generally has the connotation that you mentioned, to disappoint someone.

Like if you asked me to go on a date, I say no, you could say "He turned me down." If I said yes, then failed to show up for the date, you might say "He really let me down."

[mlmooney89]

Yeah FatAndFaithless is right. Also turning someone down usually is in regards to things like dates or romantic situations.

[wiploc]

To turn someone down is to reject an offer, "No, I won't go to the prom with you."

To let someone down is to disappoint them, "Sorry, I never finished installing the escape ladders from the mine."

[rado84]

I see. Thank you for the answers. I didn't know that the first one is related to requests.

[Edwardo Piet]

You can let yourself down, but you can't turn yourself down

[rado84]

You can let yourself down, but you can't turn yourself down

I could turn myself down, if I had a clone of myself. Not that I would, though.

[Alex K]

One typically turns down offers, for example

[Cyberman]

I chose to turn down the request in the OP. Sorry to let you down.

[Whateverist]

You can let yourself down, but you can't turn yourself down

Of course you can.  How do you think I lost all that weight?