Equus

Part of speech: noun (n.)

1. A genus of mammals, including the horse, ass, etc.

2. .

3. The termination of many English words, denoting the agent; -- applied either to men or things; as in hater, farmer, heater, grater. At the end of names of places, -er signifies a man of the place; as, Londoner, i. e., London man.

4. A suffix used to form the comparative degree of adjectives and adverbs; as, warmer, sooner, lat(e)er, earl(y)ier.