freakish

Concise Oxford English Dictionary © 2008 Oxford University Press:
freak/friːk/

▶noun

• 1 (also freak of nature) a person, animal, or plant with a physical abnormality.

• 2 [often as modifier] a very unusual and unexpected event: a freak storm.

• 3 informal a person who is obsessed with a particular activity or interest: a fitness freak.

• 4 archaic a whim.

▶verb

• 1 (usu. freak out) informal behave or cause to behave in a wild and irrational way.

• 2 archaic fleck or streak randomly.

– derivatives
freakish adjective,
freakishly adverb,
freakishness noun.

– origin C16: prob. from a dial. word.