WordWeb Online

1. Pleasantly without extremes
   "balmy days and nights"
   - mild, soft
    
2. [archaic] Informal or slang term for mentally irregular
   "it used to drive my husband balmy"
   - barmy, bats, batty, bonkers, buggy [N. Amer], cracked, crackers, daft, dotty, fruity, haywire, kooky, kookie, loco, loony, loopy, nuts, nutty, round the bend, around the bend, wacky, whacky, daft as a brush [Brit], wacko, round the twist [Brit]

Derived forms: balmier, balmiest

See also: balm, clement, insane