Whirl or swirl (4)
I believe the answer is:
eddy
I believe this is a double definition.
'whirl' is the first definition.
(I know that whirl can be written as eddy)
'swirl' is the second definition.
(I know that swirl can be written as eddy)
(Other definitions for eddy that I've seen before include "Swirl; small whirlpool" , "Swirling current" , "current revolution" , "Religious woman" , "Chap" .)