Learner's definition of FLIER
a person or animal that flies
These birds are graceful fliers.
Charles Lindbergh was the first flier [=pilot] to fly solo across the Atlantic.
a fearful/nervous flier [=airplane passenger]
a frequent flier [=a person who flies often on a particular airline]
◊ The usual spelling of this sense in U.S. English is flier. The usual British spelling is flyer.
a piece of paper that has something printed on it (such as an advertisement or an announcement) and that is given to many people
take a flier
to do something that could have either good or bad results
to do something risky
— often + on