1. To bend or incline toward a position in front of something or oneself. I leaned forward to grab my essay from the professor. The tree leaned so far forward in the wind that I would it would break.

2. To bend or tilt someone or something forward. In this usage, a noun or pronoun is used between "lean" and "forward." The doctor leaned the man forward to examine the wound on his lower back. I leaned the box forward to try to read the label on the bottom.