-er

(added to verbs) A person or thing that does an action indicated by the root verb; used to form an agent noun.

(added to verbs, informal) A person or thing to which the root verb can satisfactorily be done.

(added to a noun denoting an occupation) A person whose occupation is (the noun).

(added to a number, measurement or noun denoting a quantified set) A name for a person or thing that is based on a number (with or without a noun).

(slang, chiefly entertainment, with few limitations) Used to form nouns shorter than more formal synonyms.

(informal, added to a noun) One who enjoys.

(added to nouns) Person who is associated with, or supports a particular theory, opinion, or belief.