probably better somewhere else but...

thinking about how to refer to junctions.

Here's what I'm thinking:

verb: connect, plus (neither are directional)
eg. Connect A to B.  Plus A to B.

On A+B
 
A+B+C:  plus card, connection card
eg. Connections: We connect "Introduction" to other cards

C: plussee, connectee
eg. Connection Partners: "Introduction" is connected to us.

A: pieces, connected pieces
eg. Connected Pieces: We're connected to form "Introduction+X"