Hello Safaa, "butt in" means to break into a conversation. Alice broke into the mother's speech about how to fix the sweater. to butt in someone or something means to interrupt someone or something. Example: "Tom butted in on Safaa to tell her that the mail had come."

Butt in = interrupt 1) Don't butt in when I'm talking. 2) She keeps butting in during our conversation. 3) It's rude to butt in when others are talking.

I'll just add a rough definition of "butt" - something which is blunt, rounded and perhaps heavy. The end of something (eg. cigarette butt). So "to butt" means to use a blunt/heavy/rounded thing to hit at something else. Hope that helps with the idea behind the expression!

I just want to add that when using 'butt in' on a situation, we mean 'to become involved in a situation that does not concern you'. It is used in an informal context here, and 'interfere' is a synonym for 'butt in' in this case. 'I didn’t ask you to butt in on my private business.' I also want to give you another expression (phrasal verb) which means 'interrupt a conversation'. It is 'break in (on something). We use it to mean 'to interrupt' or 'disturb' something: 'She longed to break in on their conversation but didn’t want to appear rude.' ‘I didn’t do it!’ she broke in.

One thing that should be mentioned - a person can "butt in" to a situation as well as a conversation. "The boy and the girl were having a good night kiss at her door when her father butt in and sent the boy home."