even/much/still less

much less

1. A lot less. We've had much less foot traffic since construction started. This magazine has much less content than it used to.
2. And especially not; and even less so. The phrase is used to indicate that something is especially not the case, even less so than what was previously mentioned. We don't have enough money for new car, much less a luxury SUV. He barely looked at me, much less smiled.
See also: less, much
Farlex Dictionary of Idioms.

much less

And certainly not, as in He rarely talks about his outside activities, much less his family. The earliest record of this idiom is in John Milton's Paradise Lost (1671): "The world thou hast not seen, much less her glory."
See also: less, much
The American Heritage® Dictionary of Idioms by Christine Ammer.

even/much/still ˈless

and certainly not: I don’t want even to see her, much less speak to her. I don’t like beer, even less do I like warm, weak English beer.
See also: even, less, much, still
Farlex Partner Idioms Dictionary
See also:
  • much less
  • go off the boil
  • under (someone's or something's) shadow
  • under the shadow of (someone or something)
  • in the shadow of (someone or something)
  • in/under the shadow of
  • less than
  • less than (something)
  • the path less traveled
  • a little frog in a big pond