'Thinker' definitions:

Definition of 'thinker'

From: WordNet
noun
An important intellectual; "the great minds of the 17th century" [syn: thinker, creative thinker, mind]
noun
Someone who exercises the mind (usually in an effort to reach a decision)

Definition of 'Thinker'

From: GCIDE
  • Thinker \Think"er\, n. One who thinks; especially and chiefly, one who thinks in a particular manner; as, a close thinker; a deep thinker; a coherent thinker. [1913 Webster]