From Longman Dictionary of Contemporary English build up phrasal verb 1 increase gradually if something builds up somewhere, or if you build it up, it gradually becomes bigger or greater the rate at which the pension builds up build something ↔ up The museum has built up a fine art collection. → build-up 2 develop build something ↔ up to make something develop or form build something ↔ up into He’s built up the family firm into...