The Collaborative International Dictionary of English v.0.48:

Gaffer \Gaf"fer\ (g[a^]f"f[~e]r), n. [Possibly contr. fr.
   godfather; but prob. fr. gramfer for grandfather. Cf.
   Gammer.]
   1. An old fellow; an aged rustic.
      [1913 Webster]

            Go to each gaffer and each goody.     --Fawkes.
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   Note: Gaffer was originally a respectful title, now
         degenerated into a term of familiarity or contempt when
         addressed to an aged man in humble life.
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   2. A foreman or overseer of a gang of laborers. [Prov. Eng.]
      [1913 Webster]

WordNet (r) 3.0 (2006):

gaffer
    n 1: an elderly man [syn: old-timer, oldtimer, gaffer,
         old geezer, antique]
    2: an electrician responsible for lighting on a movie or tv set
    3: a person who exercises control over workers; "if you want to
       leave early you have to ask the foreman" [syn: foreman,
       chief, gaffer, honcho, boss]