shark Definition

shark
noun

1. Any of 400 species of large cartilaginous fishes which have remained virtually unchanged for millions of years, with a spindle-shaped body covered with tooth-like scales, and a tail fin with a long upper lobe and shorter lower lobe.
2. colloq
A ruthless or dishonest person, especially one who swindles, exploits or extorts.

Etymology: 16c in sense 2: perhaps from German Schurke scoundrel.