-er³

Also ‑ers.

Colloquial or humorous nouns and adjectives.

Probably an extended use of ‑er¹.

Examples are footer (football), rugger (rugby), brekker (breakfast), and soccer (the last from an abbreviated and clipped form of Association Football). The style is to abbreviate—and often to distort—the root word, and then add ‑er. This was originally Rugby School slang, later adopted at Oxford University about 1875, then extended into general use. Most examples have since disappeared; only soccer has become standard English. A few are spelled ‑ers (Twickers for the rugby ground at Twickenham), though most in this ending are adjectives: bonkers and crackers (mad), preggers (pregnant), starkers (stark naked).