expression, godan verb (-ru)
wedge one's way in; push in; interrupt; intervene
Describes physically or figuratively forcing oneself into a space, conversation, or situation, often between people or things. Can be used for breaking into a line, interrupting an argument, or stepping in to mediate.
彼は列に割って入った。
He wedged his way into the line.
You'd better not step in between their quarrel.