thread
thread: n. [Usenet, GEnie, CompuServe] Common abbreviation of
`topic thread', a more or less continuous chain of postings on a
single topic. To `follow a thread' is to read a series of Usenet
postings sharing a common subject or (more correctly) which are
connected by Reference headers. The better newsreaders can present
news in thread order automatically. Not to be confused with the
techspeak sense of `thread', e.g. a lightweight process.
Interestingly, this is far from a neologism. The OED says: "That
which connects the successive points in anything, esp. a narrative,
train of thought, or the like; the sequence of events or ideas
continuing throughout the whole course of anything;" Citations are
given going back to 1642!