Definition of freak-out:
(n) :
(slang, chiefly derogatory) A person who is extremely abnormal in appearance, social behavior, sexual orientation, gender identity, or business practices; an oddball, a unique person, originally in a displeasing or alienating way.
(n) :
An enthusiast, or person who has an obsession with, or extreme knowledge of, something.
(n) :
(dated outside certain expressions) Someone or something that is markedly unusual or unpredictable.
(n) :
(bodybuilding) A person whose physique has grown far beyond the normal limits of muscular development; often a bodybuilder weighing more than 260 pounds (120 kg).
(n) :
A drug addict.
(n) :
(informal, sometimes endearing) A very sexually perverse individual.