c. 1400, nome, "deprived of motion or feeling," literally "taken, seized," from past participle of nimen "to take, seize," from Old English niman "to take, catch, grasp" (from PIE root *nem- "assign, allot; take"). The unetymological -b (to conform to comb, limb, etc.) appeared 17c. The notion is of being "taken" with palsy, shock, and especially cold. Figurative use from 1560s.
1550s, from numb (adj.). Related: Numbed; numbing.