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1. verb To stop bothering someone or something. A noun or pronoun can be used between "let" and "alone." Why do you keep picking at that scab on your knee? Let it alone already! For the last time, let your brother alone—he needs to study!
2. expression Not to mention. The phrase is used to emphasize that if other more significant or pressing things are not possible or cannot be accommodated, a lesser thing certainly is not or cannot either. I hardly had time to brush my teeth this morning, let alone do my hair! We can't afford a vacation, let alone a trip to Disney World.
let someone or something aloneand leave someone or something alone; leave someone or something be
to avoid touching, bothering, or communicating with someone or something. Leave me alone. I don't want your help. Let it alone! Don't touch it! It may be hot!
let alone someone or something
not to mention or think of someone or something; not even to take someone or something into account. (Fixed order.) Do I have a dollar? I don't even have a dime, let alone a dollar. I didn't invite John, let alone the rest of his family.
1. See leave someone alone.
2. Not to mention, as in We have no room for another house guest, let alone an entire family. [c. 1800]
let aˈloneused after a statement to emphasize that because the first thing is not true or possible, the next thing cannot be true or possible either: I wouldn’t speak to him, let alone trust him or lend him money. ♢ She didn’t even apologize, let alone offer to pay for the damage.
Not to mention; much less: "Their ancestors had been dirt poor and never saw royalty, let alone hung around with them" (Garrison Keillor).