rot.

WordReference Random House Learner's Dictionary of American English © 2026

rot /rɑt/   v., rot•ted, rot•ting, n., interj. 
v. 

1. to (cause to) undergo decay: [no object]
   The dead leaves rotted in the soil.
   [~ + object]
   Overwatering will rot the houseplants.
2. to become weak because of decay:
   [no object* (~ + away)] The disease was taking its toll, and his body was rotting away before our eyes.
3. to become gradually worse, as from being in jail:
   [no object] hoped the killer would rot in jail.

n. [uncountable]

4. the state of being rotten;
   decay.
5. rotting or rotten matter:
   dry rot.
6. moral or social decay or decline:
   rot and corruption in the regime.
7. Pathology a disease caused by an infection and resulting in decay.
8. nonsense.

interj. 

9. (used to express disagreement or disgust):
   Oh, rot! I don't believe you!

WordReference Random House Unabridged Dictionary of American English © 2026

rot  (rot), v., rot•ted, rot•ting, n., interj. 
v.i. 

1. to undergo decomposition;
   decay.
2. to deteriorate, disintegrate, fall, or become weak due to decay (often fol. by away, from, off, etc.).
3. to languish, as in confinement.
4. to become morally corrupt or offensive.

v.t. 

5. to cause to rot:
   Dampness rots wood.
6. to cause moral decay in;
   cause to become morally corrupt.
7. to ret (flax, hemp, etc.).

n. 

8. the process of rotting.
9. the state of being rotten;
   decay;
   putrefaction:
   the rot of an old house.
10. rotting or rotten matter:
    the rot and waste of a swamp.
11. moral or social decay or corruption.
12. Pathology any disease characterized by decay.
13. [Plant Pathol.]
    • Plant Diseases any of various forms of decay produced by fungi or bacteria.
    • Plant Diseases any disease so characterized.
14. Veterinary Diseases a bacterial infection of sheep and cattle characterized by decay of the hoofs, caused by Fusobacterium necrophorum in cattle and Bacteroides nodosus in sheep.
15. nonsense.

interj. 

16. (used to express disagreement, distaste, or disgust.)

• Old Norse rot (perh. partly derivative of the verb, verbal); compare ret, rotten)
• bef. 900; (verb, verbal) Middle English rot(t)en, Old English rotian, cognate with Frisian rotsje, Dutch rotten; (noun, nominal) Middle English, perh.

Synonyms

• 1. mold, molder, putrefy, spoil. See decay. 
• 9. decomposition, mold.

Antonyms

• 4, 6. purify.

ROT, 

1. rule of thumb.

rot., 

1. rotating.
2. rotation.