"The terms id̲j̲tahada / id̲j̲tihād signifying originally, in various contexts: to exert oneself, using one’s intellectual faculties, for (the good of) the Muslim community or of Islam".
Calmard, J., “Mud̲j̲tahid”, in: Encyclopaedia of Islam, Second Edition, Edited by: P. Bearman, Th. Bianquis, C.E. Bosworth, E. van Donzel, W.P. Heinrichs. Consulted online on 17 February 2017