buff up

Verb

buff up (third-person singular simple present buffs up, present participle buffing up, simple past and past participle buffed up)

1. (idiomatic, transitive) To improve.
   • […] Mr. Kurz was quickly seen in Europe as the poster boy of an ascendant right for a new generation, a political Wunderkind who had salvaged conservatism by borrowing the far right’s agenda, buffing it up and bringing it into the mainstream.2021 October 17, Katrin Bennhold, “Fake Polls and Tabloid Coverage on Demand: The Dark Side of Sebastian Kurz”, in The New York Times, →ISSN
2. (transitive) To shine; to make shiny.
3. (idiomatic, intransitive) To become more muscular.
4. (idiomatic, intransitive) To study hard to learn a particular subject.
   • I'll need to buff up on my Italian before my trip to Genoa.

   Synonyms:

   cram