1
general::
1. Enter or engage in, be drawn into, as in I told Dad not to fall into conversation with them. [Late 1400s] 2. See FALL IN, def. 1. 3. Be naturally divisible into, as in These students fall into three categories. [First half of 1600s] 4. fall into error or sin. Be drawn into bad behavior, as in I fell into error when I started spending time with the wrong crowd. This usage, like FALL FROM GRACE, originally alluded to religious concerns. It is now used less often and more loosely. [Late 1100s] 5. fall into a trap. Be deceived, unknowingly become involved in something. For example, By admitting I had free time, I fell into the trap of having to help him with his work. Also see under FALL IN; FALL IN LINE; FALL IN PLACE.
American Heritage Idioms