1. To bend, tilt, or suspend oneself out of something. The helicopter pilot leaned out of the cockpit and signaled for us to get in. Quit leaning out the window like that—you're making me nervous!

2. To bend, tilt, or suspend someone or something out of something. In this usage, a noun or pronoun is used between "lean" and "out." The gangsters leaned him out of the window, threatening to drop him if he didn't pay them what he owed. I leaned the bookcase out the door so Jerry could grab it from the top, then we hauled it out to his truck together.