The "m" in E=mc^2 (4)
I believe the answer is:
mass
(Other definitions for mass that I've seen before include "The proletariat" , "Church service - collection" , "Large amount, body" , "RC ceremony" , "Lump of material" .)
I believe the answer is:
mass
(Other definitions for mass that I've seen before include "The proletariat" , "Church service - collection" , "Large amount, body" , "RC ceremony" , "Lump of material" .)