[much less] conj (1710): to say nothing of--used esp. in negative contexts to add to one item another denoting something less likely "can hardly grow, much less ripen, till the stock is in the earth --Jonathan Swift" "he is never going to get out of the eighth grade, much less ever make it to college --Thomas Meehan"
MUCH LESS
Meaning of MUCH LESS in English
Merriam-Webster English vocab. Английский словарь Merriam Webster. 2012