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.
let alone do something
and to an even greater degree do something We were trapped in a situation you can barely imagine, let alone understand.
Usage notes: used to emphasize the extreme character of something
