Meaning of “thread” - Learner’s Dictionary

thread

noun uk us /θred/
MATERIAL [ C, U ]

a long, thin piece of cotton, wool, etc that is used for sewing:

a needle and thread
CONNECTION [ C ]

the connection between different events or different parts of a story or discussion:

By that point I'd lost the thread of the conversation.
INTERNET

[ C ] a group of pieces of writing on the Internet in which people discuss one subject

(Definition of “thread noun” from the Cambridge Learner’s Dictionary © Cambridge University Press)