What is a word for someone who uses a word excessively in conversation? For example, using the same swear word in every sentence.
When speaking, we often use filler words when we are talking to indicate that a pause in speech is temporary. Often we do this when we're thinking about what to say next, and we want the listener to know that although we have stopped talking, we're going to continue again shortly, so "stay tuned." And in many cases we aren't even aware that we're doing this.
Common examples of this are sounds like um, like, and er, or phrases like you know or so anyway but some people will use other specific words this way. For example, I know someone who says the word ultimately repeatedly. Every conversation with him is sure to have that word in it at least twice.
The problem is, we all do this to some extent, it's pretty much universal, to the extent that up to 20% of all speech can be such words. That makes it unlikely that there's a special word just for people who do this.