A volatile liquid added to paints to lower viscosity (7)
I believe the answer is:
thinner
(Other definitions for thinner that I've seen before include "More slim" , "More flimsy" , "Skinnier" , "less strong" , "Diluting agent" .)
I believe the answer is:
thinner
(Other definitions for thinner that I've seen before include "More slim" , "More flimsy" , "Skinnier" , "less strong" , "Diluting agent" .)