Definition of "fall in"

fall in

verb
third-person singular simple present falls in, present participle falling in, simple past fell in, past participle fallen in
1. (intransitive) To collapse inwards.
2. (intransitive, military) Of a soldier, to get into position in a rank.
3. To come to an end; to terminate; to lapse.
4. To become operative.
  Quotations
  The reversion, to which he had been nominated twenty years before, fell in.
  1841, Thomas Macaulay, Lord Byron and The Comic Dramatists of the Restoration