1. To become decayed or decomposed and start disintegrating. Often used in passive constructions. You can see that the floorboards are starting to rot out, so we'll need to pull everything up and start from scratch. It wasn't until we were already on the water that I realized the hull of the ship had rotted out.
2. To cause something to decay or decompose and begin disintegrating as a result. In this usage, a noun or pronoun can be used between "rot" and "out." Damp has rotted out the wood beneath the staircase, meaning the whole thing could collapse at any second. You're going to rot Zoe's teeth out with the amount of sugary snacks you let her eat!
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
to decompose and fall out. If you don't clean your teeth regularly, they'll rot out! Some of the rafters in the shed rotted out, but we replaced them easily.
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.
1. To become completely hollow or ruined by decay or decomposition: If you don't see a dentist, your teeth will rot out. The abandoned building might collapse because its walls have rotted out.
2. To cause something to become completely hollow or ruined by decay or decomposition: The water from the leaky sink rotted out the floor boards. All that candy will rot your teeth out.
The American Heritage® Dictionary of Phrasal Verbs. Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.