From Longman Dictionary of Contemporary Englishfill up phrasal verb1 FULLif a container or place fills up, or if you fill it up, it becomes full with Her eyes filled up with tears.fill something ↔ up Shall I fill the car up (=with petrol)?2 fill (yourself) up informalFULL to eat so much food that you cannot eat any morefill (yourself) up with/on Don’t fill yourself up with cookies. He filled up on pecan pie.3 DFFULL fill somebody up informal food that fills you up makes you feel as though you have eaten a lot when you have only eaten a small amount → fill→ See Verb table
Examples from the Corpus
fill up• About half an hour before the performance, the theatre starts to fill up.• If the oil tank is less than half full, tell them to fill it up.• The drought has ended at last, and the reservoirs are filling up again.• The waiter filled up everyone's glasses.• I filled up the sandbox with some more sand.eyes filled up with tears• But the minute he mentioned the name Mrs Hooper's eyes filled up with tears.fill with/on• Joseph is a disgruntled Brooklyn teenager who, when he doesn't get into Columbia, fills up with ennui.• Should I fill up with petrol just in case?• The prize, though, goes to the mite who offered to watch my car as I was filling up with petrol.• I saw the fields... filling up with regiments and columns and armies of gray. y..• The tide was close in by now, and his footprints behind him filled up with water, gleaming.• Perhaps there is no greater feeling of powerlessness, and despair, than seeing a home fill up with water.• The streets are filling up with water...• Those dry rice paddies that we walked through, we could swim through; they all filled up with water.From Longman Business Dictionaryfill up phrasal verb [intransitive] to gradually become full of people, things, or a substanceShares on the Stock Market began to rise, and industry reported order books filling up. withThe Antrim Technology Park is filling up with high technology software companies. → fill→ See Verb table 