(linguistics) a word or phrase that marks a boundary in a discourse, typically as part of a dialogue. Discourse markers often signal topic changes, reformulations, discourse planning, stressing, hedging, or backchanneling.
Common discourse markers used in the English language include "you know", "or whatever", "actually", "basically", "like", "I mean" and "OK".
English Wiktionary. Available under CC-BY-SA license.