1560s, "violent encounter of armed forces or a pair of warriors," a military term, from French choc "violent attack," from Old French choquer "strike against," probably from Frankish, from a Proto-Germanic imitative base (compare Middle Dutch schokken "to push, jolt," Old High German scoc "jolt, swing").

The general sense of "a sudden blow, a violent collision" is from 1610s. The meaning "a sudden and disturbing impression on the mind" is by 1705; the sense of "feeling of being (mentally) shocked" is from 1876.

The electrical sense of "momentary stimulation of the sensory nerves and muscles caused by a sudden surge in electrical current" is by 1746. The medical sense of "condition of profound prostration caused by trauma, emotional disturbance, etc." is by 1804 (it also once meant "seizure, stroke, paralytic shock" 1794).

Shock-absorber is attested from 1906 (short form shocks attested by 1961); shock wave is from 1907. Shock troops (1917), especially selected for assault work, translates German stoßtruppen and preserves the word's original military sense. Shock therapy is from 1917; shock treatment from 1938.