Idiom
give a thumbs down someone(give a) thumbs down to (someone/something)
to show disapproval of or opposition to someone or something.My husband gave a big thumbs down to my idea of getting a new car.
Usage notes: often used in the form give the thumbs down (to something):
Voters gave the thumbs down to building a new firehouse.
Opposite of: (give a) thumbs up to (someone/something)