teratoid \TER-uh-toid, adjective:

Resembling a monster.

They wandered, amazed, through street after street of these teratoid villas and they concluded that the architecture of Knokke-le-Zoute was unique and far more disrespectful to the eye than that of any other maritime settlement they had ever seen, worse, by far, than Brighton or Atlantic City.
— Jean Stafford, “The Children’s Game,” The Collected Stories of Jean Stafford, 1958

Later she rechecked the engraving and was appalled to see that Lincoln had lain on what appeared to be a teratoid, golden oak, four-poster bed.
— William Manchester, The Death of a President, November 20-November 25, 1963

Teratoid was coined in the 1870s. The root terat- is a Greek combining form that means “indicating a monster.”