I want to find suitable words to describe a person who always jumps in the middle of a conversation and starts talking without considering or waiting for other people to finish their sentences.
If you're looking for verbs, then there are:
to stop someone from speaking by saying or doing something, or to cause an activity or event to stop briefly:
[ I ] Please don’t interrupt until I’m finished.
[ T ] The picnic was interrupted by a rain shower.
The following are a number of related, casual verbs:
- butt in
to interrupt a conversation or discussion or someone who is talking:
He kept on butting in with silly comments.
- chime in
to speak in a conversation, esp. by interrupting:
Everyone at the table began to chime in with their opinions.
- chip in
mainly UK informal
to interrupt a conversation in order to say something:
I'll start and you can all chip in with your comments.
- cut in
to interrupt what someone is saying by saying something yourself:
I was just talking to Jan, when Dave cut in (on us/our conversation).
- horn in
to try to become involved in a discussion or activity when you are not wanted:
She's always horning in on our conversations.
I can't think of any good words or idioms that include both someone who talks too much and someone who interrupts others, but if you are just talking about someone who talks too much, you could call them:
Or describe them as:
- Liking the sound of their own voice / Loving the sound of their own voice
To enjoy hearing oneself talk because one is pompous and/or self-centered.
If you are not worried about encompassing someone who talks too much, but are more interested in saying that they interrupt a lot, you could call them:
- An interrupter
one that interrupts
Although, this is not in common usage, and it can be used for "a device for interrupting an electric current usually automatically" (not that anyone would confuse it for that use in context).