on-line (Adjective) — Available over the Internet.
on-line (Adjective) — Being in progress now. ex. "on-line editorial projects"
on-line (Adjective) — (transportation) on a regular route of a railway, bus or airline system. ex. "on-line industries"
on-line (Adjective) — (computing) connected to a computer network or accessible by computer. ex. "an on-line database"