give a definition of 1) a robot 2) a machine 3) a human

robot: a machine that can perform a complicated series of tasks automaticallymachine
 machine :(often in compounds) a piece of equipment with moving parts that is designed to do a particular job. The power used to work a machine may be electricity, steam, gas, etc. or human powerhuman [only before noun] of or connected with people rather than animals, machines or godsthe 
human body/brainhuman anatomy/activity/behaviour/experiencea terrible loss of human lifeContact with other people is a basic human need.This food is not fit for human consumption.