I'd always assumed it was derived from French but according to Wiki:
"The term comrade generally means 'mate', 'colleague', or 'ally', and derives from the Spanish and Portuguese, term camarada, literally meaning 'chamber mate', from Latin camera, meaning 'chamber' or 'room'. It may also specifically mean "fellow soldier""
"The term comrade generally means 'mate', 'colleague', or 'ally', and derives from the Spanish and Portuguese, term camarada, literally meaning 'chamber mate', from Latin camera, meaning 'chamber' or 'room'. It may also specifically mean "fellow soldier""