let alone vs variate

let alone

conj
  • Much less; to say nothing of; used after one negative clause to introduce another, usually broader and more important clause, whose negation is implied by the negation of the first. However either of these instances mentioned can be applied with the use of let alone. 

  • not to mention, as well as; used after one item, to introduce a further item which is entailed by the first. 

verb
  • To leave alone, let be; to stop bothering. 

variate

noun
  • The measured magnitude of a variable. 

  • random variable 

  • A variable, often the set of x values plotted on a graph. 

  • A measurable quantity capable of taking on a number of values. 

verb
  • To alter; to vary; to make or become different. 

How often have the words let alone and variate occurred in a corpus of books? (source: Google Ngram Viewer )