to gradually get closer to a person, car etc that you are chasing:
Quick - they're gaining on us!
WORD CHOICE: WORD CHOICE: gain, earn, getDo not use gain to mean 'get money for work you do'. Use earn• people earning less than £10,000 per year • How much does he earn?Gainmeans to get something useful or necessary, whether or not you deserve it• I have gained a lot of useful experience. • Her problems seem to have gained her more support from the public.Use earn rather than gainto say that you get something because you deserve it• Through hard work you will earn the respect of your colleagues.Get can be used as a less formal way of saying gain or earn• I get $20 an hour. • He has started to get a reputation for being awkward.
Definition from the Longman Dictionary of Contemporary English Advanced Learner's Dictionary.