A Terminal Node Controller is essentially a smart modem designed for packet radio. It is the device used to interface the radio and terminal. This is a vague term, it refers to a communications link between two widely separated communications facilities. A wormhole has the ability of making the two distant facilities appear to be connected directly to each other. Such a wormhole exists between the Richmond and the Tidewater area.
Wormholes are usually landline based.
This article is an excellent source of information for people new to packet.