[no object]

1 . to feel or show strong emotion (such as anger) even though you try to control it

• He seethed at his brother’s success.

— often + with

• He seethed with anger/jealousy.
• The letter seethes with resentment.
• a seething letter

2 . to be in a state of constant activity

• We found ourselves in the middle of a seething crowd.

— often used as (be) seething with

• The island is seething with tourists. [=there are very many tourists moving around on the island]
• The field was seething with crickets.
• His brain was seething with ideas.