being effective without wasting time or effort or expense, Making good, thorough, or careful use of resources; not consuming extra Especially, making good use of time or energy, Causing less waste or requiring less effort than comparable devices or methods Used in combination, noun_ An efficient cause; a prime mover, In mathematics, a quantity multiplied by another quantity to produce the quantity of which it is said to be an efficient; a factor, One who is efficient or qualified; specifically, in the volunteer service of Great Britain, one who has attended the requisite number of drills, and in respect of whom the corps receives the capitation grant paid by government