think ‧ er /ˈθɪŋkə $ -ər/ BrE AmE noun [countable]
[ Word Family: noun : ↑ think , ↑ rethink , ↑ thinker , ↑ thinking , the unthinkable; verb : ↑ think , ↑ rethink ; adjective : ↑ thinkable ≠ ↑ unthinkable , ↑ thinking ≠ ↑ unthinking ; adverb : ↑ unthinkingly ]
1 . someone who thinks carefully about important subjects such as science or ↑ philosophy , especially someone who is famous for thinking of new ideas:
great thinkers such as Kant and Schopenhauer
2 . an independent/a positive/a free etc thinker a person who thinks in a particular way