The Collaborative International Dictionary of English v.0.48:

Tuner \Tun"er\ (t[=u]n"[~e]r), n.
   One who tunes; especially, one whose occupation is to tune
   musical instruments.
   [1913 Webster]

WordNet (r) 3.0 (2006):

tuner
    n 1: someone who tunes pianos [syn: tuner, piano tuner]
    2: an electronic receiver that detects and demodulates and
       amplifies transmitted signals [syn: radio receiver,
       receiving set, radio set, radio, tuner, wireless]