fall down phrasal verb (
see also fall)
1. be falling down if a building is falling down, it is in very bad condition:
The bridge is falling down and will need a million dollars to repair it.2. to fail because of a particular reason or in a particular way:
That’s where the whole argument falls down.fall down on He is falling down on the supervisory aspects of his job. The local authority is falling down on the job of keeping the streets clean. [TahlilGaran] Dictionary of Contemporary English ▲