1. phrasal verb If you fall behind, you do not make progress or move forward as fast as other people. [V P] ⇒ Evans had rheumatic fever, missed school and fell behind. [V P n] ⇒ Boris is falling behind all the top players. 2. phrasal verb → fall If you fall behind with something or let it fall behind, you do not do it or produce it when you should, according to an agreement or schedule. [V P + with] ⇒ He faces losing his home after falling behind with the payments. [V P] ⇒ Thousands of people could die because the relief effort has fallen so far behind. [V P n] ⇒ Construction work fell behind schedule.
COBUILD Advanced English Dictionary. Copyright © Harper Collins Publishers