English to Esperanto

[a_rahman]

I am trying to translate the word "thinker" to Esperanto
These words are all related to thinking:
pensulo
pensisto
pensanto
Which word means the one who does the thinking as a profession or hobby such as philosophers and writers?
Which word means anyone who can think, to distinguish him/her from a stupid person or an animal?
Which word means just any thoughtful person?