coral (n.)

c. 1300, from Old French coral (12c., Modern French corail), from Latin corallium, from Greek korallion; perhaps of Semitic origin (compare Hebrew goral "small pebble," Arabic garal "small stone"), originally just the red variety found in the Mediterranean, hence use of the word as a symbol of "red." Related: Coralline. Coral snake (1760) is so called for the red zones in its markings. Coral reef is attested from 1745.