Definition of Discussion thread:
Chain of written ideas or opinions (exchanged among two or more participants in an online discussion) linked in the sequence in which they were espoused by the participants. Through the use of hypertext, discussion threads allow new or old participant to start at any point and follow the entire discussion from its very beginning to its latest idea or opinion. Introduced by collaborative software such as Lotus notes, they are now an integral part of the discussion group sites.
Meaning of Discussion thread & Discussion thread Definition