backlash

Where it comes from

Backlash ordinarily means a strong negative reaction to a social, political, or cultural development. Backlash was recorded in the early nineteenth century as a machinery term, formed from back and lash, a blow or stroke. It described a backward reaction between connected parts under changing load. The image of machinery striking or moving back became a metaphor for a strong adverse reaction.

How the meaning developed

The figurative social and political sense appeared in the twentieth century.

In use

Today a backlash is a strong adverse reaction.
Before politics used it, engineers used the word for backward reaction or lost motion between connected parts.