Wiktionary
vb. 1 (context transitive idiomatic English) to improve 2 (context transitive English) to shine; to make shiny 3 (context intransitive idiomatic English) to become more muscular 4 (context intransitive idiomatic English) to study hard to learn a particular subject
Usage examples of "buff up".
You've never had to worry about anything but snapping your fingers so a servant can buff up the silver platter you're served on.
In this case, as the Middle East peace process staggered onward and the outgoing American president, hungry for a breakthrough to buff up his tar.
Eve could have poked her about it but decided being stuck in a miserable job was some excuse not to buff up for the day.
I spend half my waking time working to buff up the bod so someone else can enjoy it, and this is what I come home to?
Fourteen times he made me buff up that Quidditch cup before he was satisfied.
Someone had even managed to buff up a shine on the old pewter candlesticks.
I believe he had visions of using the Stormwardenwho had been in the Cantard for monthsas a chamois to buff up his Glory Mooncalled theory.