a small planet and the farthest known planet from the sun; has the most elliptical orbit of all the planets; "Pluto was discovered by Clyde Tombaugh in 1930"
(Greek mythology) the god of the underworld in ancient mythology; brother of Zeus and husband of Persephone
(psychology) the aggregate of the responses or reactions or movements made by an organism in any situation
the action or reaction of something (as a machine or substance) under specified circumstances; "the behavior of small particles can be studied in experiments"
(Greek mythology) the supreme god of ancient Greek mythology; son of Rhea and Cronus whom he dethroned; husband and brother of Hera; brother of Poseidon and Hades; father of many gods; counterpart of Roman Jupiter