Someone who hangs around in chat, be it webchat or IRC or even our beloved #everything, logged in, when they aren't participating in the conversation or even necessarily at the other end of the terminal.

I"dler (?), n.

1.

One who idles; one who spends his time in inaction; a lazy person; a sluggard.

2. Naut.

One who has constant day duties on board ship, and keeps no regular watch.

Totten.

3. Mach.

An idle wheel or pulley. See under Idle.

© Webster 1913.