WordNet (r) 3.0 (2006):

let alone
    adv 1: much less; "she can't boil potatoes, let alone cook a
           meal" [syn: let alone, not to mention]

Moby Thesaurus II by Grady Ward, 1.0:

110 Moby Thesaurus words for "let alone":
   abandon, abstain, abstain from, added to, along with, as well as,
   aside from, attended by, avoid, bar, barring, be conservative,
   beside, besides, butt out, coupled with, cut, dispense with,
   do nothing, do without, eschew, ex, except, except for, excepting,
   excluding, exclusive of, fight shy of, forbear, forgo,
   give place to, goldbrick, goof off, hold aloof, hold aloof from,
   hold back, hold off, in addition to, in conjunction with,
   including, inclusive of, jump, keep aloof, keep away from,
   keep back, keep clear of, keep from, keep hands off, keep in hand,
   keep remote from, leave, leave alone, leave be, leave loose ends,
   leave undone, leaving out, let be, let dangle, let go, let go by,
   linked to, make way for, malinger, miss, never touch, not butt in,
   not get involved, not interfere, not make waves, not meddle,
   not meddle with, not tamper, not to mention, not touch, not use,
   omit, omitting, oppose change, outside of, over and above,
   pass over, pass up, plus, precluding, pretermit, procrastinate,
   refrain, refrain from, reserve, save, save and except, saving,
   shirk, slack, spare, stand aloof, stand aloof from, stand pat,
   stand still, stay detached from, steer clear of, than,
   together with, trifle, turn away from, unless, waive, with,
   withhold, without