1 British English thumb a ride American English informalTTC
to persuade a driver of a passing car to stop and take you somewhere, by putting your hand out with your thumb raised:
I thumbed a lift into town.
to show that you do not respect rules, laws etc or you do not care what someone thinks of you:
a chance to thumb his nose at the college authorities
thumb through somethingphrasal verb
I began thumbing through the pages of a gardening catalogue.