do‧er /ˈduːə $ -ər/ BrE AmE noun [countable] informal someone who does things instead of just thinking or talking about them:
Dole is a doer, not a talker.
doer /ˈduː.əʳ/ US /-ɚ/
noun [C]
someone who gets actively involved in something, rather than just thinking or talking about it:
There are too many thinkers and not enough doers in this office.
[du͟ːə(r)] doers N-COUNT
If you refer to someone as a doer, you mean that they do jobs promptly and efficiently, without spending a lot of time thinking about them. Robertson was a doer, not a thinker.
