- 1[intransitive] to be extremely angry about something but try not to show other people how angry you are synonym fume She seethed silently in the corner. seethe with something He marched off, seething with frustration. seethe at something Inwardly he was seething at this challenge to his authority.
- 2[intransitive] seethe (with something) (formal) (of a place) to be full of a lot of people or animals, especially when they are all moving around The resort is seething with tourists all year round. He became caught up in a seething mass of arms and legs.
- 3[intransitive] (formal) (of liquids) to move around quickly and violently The gray ocean seethed beneath them.
NAmE//sið//Verb Forms present simple I / you / we / they seethe
he / she / it seethes
past simple seethed
-ing form seething