from The American Heritage® Dictionary of the English Language, 4th Edition
- n. Slang A mechanic, especially one who works on motor vehicles or aircraft.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A mechanic, often with the specific connotation of an automobile mechanic.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. someone whose occupation is repairing and maintaining automobiles
Dates to at least 1928. May have originated during the Industrial Revolution in Great Britain when children were used to grease the large rotating axles which were used to transfer power from one centralized steam engine to all of the machines on the factory floor. These children, covered in grease and crawling in the tight spaces in the ceilings, were equated with monkeys. (Wiktionary)