What is "tailfins"

Usage examples of "tailfins".

Behind her in the body of the ovoid vehicle, fur-clad children crowded at the rim, scrambling up on the high tailfins for a better look at us.

An inner hatch closed underneath its tailfins, protecting the other probes from backfire.

Cadillac, one of those models with massive tailfins and with what seemed to be five tons of chrome grillwork.