The Collaborative International Dictionary of English v.0.48:
blue-collar \blue-collar\ adj. 1. of or designating work or workers in industry not requiring well-groomed appearance. [Narrower terms: industrial] white-collar [WordNet 1.5] 2. of those who work for wages especially manual or industrial laborers. [Narrower terms: lower-class, low-class] Syn: propertyless, wage-earning, working-class. [WordNet 1.5]