1. Ready fOR use. E.g. "The graph plotter' s fixed and on-line again". 2. Interactive as opposed to batch. Accessible via a computer (ORterminal), rather than on paper OR other medium. 3. Of a user, actively using a computer system, especially the Internet. E.g "I haven' t been on-line fOR three days." "On-line" should be hyphenated because it is compounded from two wORds but the hyphen is often omitted in names of ORganisations OR services. (1998-12-22)