thinker

noun

1. One who spends time thinking, contemplating or meditating.

   “The doer and the thinker No allowance for the other.”

2. An intellectual, such as a philosopher or theologian.

   “From his studies of these thinkers and activists, Mr. Obama took what he called the “Niebuhrian” lesson that we can have “a cleareyed view of the world and the realities of cruelty and sin and greed and violence, and yet, still maintain a sense of hope and possibility, as an act of will and leap of faith.””

3. (slang)The brain; the mind.

   “"Well, I tried to do like you and grandfather say; don't use my thinker, use imagination."”

4. (slang)A poser; a conundrum that requires some thinking.

   “HANK: The NRA is a Washington D.C. based organization. Are you telling me you support Washington D.C.? DALE: That's a thinker.”