loco
lo-co
noun
A railway engine used for pulling trains.
"The old steam loco pulled the carriages."
adjective
Informal term for being mentally unstable or crazy.
"Don't go loco over such a small thing."
Thesaurus
Synonyms: fruity, kooky, balmy, nuts, buggy, loopy, bats, whacky, wacky, loony, barmy, around the bend