Gram. the word or words denoting the person or thing indirectly affected by the action of the verb: it generally names the person or thing to which something is given or for which something is done (Ex.: him in “give him the ball,” “do him a favor”)
See indirect object in American Heritage Dictionary 4
noun
An object indirectly affected by the action of a verb, as me in Sing me a song and turtles in He feeds turtles lettuce.