Definitions

1. adjective

Relating to or resembling a placoid scale or placoid scales

“The placoidean scales on the shark’s body provided protection against predators.”

2. noun

A placoid scale or placoid scales

“The placoidean covering the shark’s skin was made up of small, tooth-like scales.”

3. noun

A group or type of sharks characterized by placoid scales

“The placoidean sharks were found in the ancient seas, with fossilized remains discovered by paleontologists.”