Synonyms for Psycho:

adj.

crazy (adjective)
insane, deranged, berserk, delirious, batty, lunatic, kooky, nutty, maniacal, demented.
demented (adjective)
hysterical, frenzied, schizoid.
insane (adjective)
feverish, frenzied, mad, batty, crazy, kooky, Crack-brained, demented, psychotic, berserk, unbalanced, deranged, irrational, blithering, insane, maniacal, neurotic, nutty, delirious, lunatic, babbling, schizoid, brain-sick, hysterical.
lunatic (adjective)
madman.
psycho (adjective)
loony, psychopathic, screwy, mad, crazy, psychotic, crazed, unbalanced.

n.

despot, brute, beast, ogre, sadist, Genghis Khan, monster, savage, animal. dwarf, cripple, cabbage, imbecile, madman, humpback, hunchback, madwoman, backward. lunatic (noun)
madman, neurotic.
mad (noun)
screwy, psychopathic, crazed, loony.
mad person (noun)
imbecile.
person (noun)
psychotic, psychotic person.
psycho (noun)
psychotic, psychotic person.

Other synonyms:

Genghis Khan, despot, sadist. monster, ogre. brute. animal, savage. Other relevant words:
humpback, imbecile, psychotic person, crazed, savage, sadist, madman, ogre, hunchback, beast, cripple, dwarf, psychopathic, cabbage, screwy, loony, monster, animal, brute, despot, madwoman, backward.