To insert something (or oneself) between other things.
To interrupt a conversation by introducing a different subject or making a comment.
To intervene in a dispute, or in a conversation.
To be inserted between parts or things; to come between.
To offer (one's help or services).
To bring (something) into practice.
To cause (someone) to be acquainted (with someone else).
To add (something) to a system, a mixture, or a container.
To make (something or someone) known by formal announcement or recommendation.