An opposite meaning. / A nonsensical idea; a contradiction in terms; something that contradicts an established principle, architectural or musical style, etc.

plural of countershading

selection that removes unwanted characteristics / (evolutionary theory) dysgenic selection (that has the opposite effects of natural selection)

A shock that travels in the opposite direction to an applied impulse

plural of countersanction

A sanction imposed in response to another sanction.

A scheme set up in opposition to another; a counterplot.

plural of counterscheme

plural of countershock

antiscientific