[WAITS, via BSD UNIX]
1. n. A program that displays a particular user or all users logged on the system or a remote system. Typically shows full name, last login time, idle time, terminal line, and terminal location (where applicable). May also display a plan file left by the user.
2. vt. To apply finger to a username.
3. vt. By extension, to check a human's current state by any means.
"OK, finger Lisa and see if she's idle."
4. Any picture (composed of ASCII characters) depicting 'the finger'. Originally a humorous component of one's plan file to deter the curious fingerer (sense 2), it has entered the arsenal of some flamers.