online

[on-lahyn, awn-] /ˈɒnˈlaɪn, ˈɔn-/
adjective
1.
operating under the direct control of, or connected to, a main computer.
2.
connected by computer to one or more other computers or networks, as through a commercial electronic information service or the Internet.
3.
of or denoting a business that transmits electronic information over telecommunications lines:
an online bookstore.
4.
available or operating on a computer or computer network:
an online dictionary.
5.
by means of or using a computer:
online shopping.
6.
Radio. (of a network) supplying affiliated stations with all or a substantial part of their programming.
7.
Television. of or pertaining to the final editing of a videotaped program.
8.
done or accomplished while in operation or active service:
online maintenance.
9.
located on major routes or rail lines:
online industries.
adverb
10.
with or through a computer, especially over a network.
Also, on-line, on line.
Compare offline.
Origin
1945-50
British Dictionary definitions for on-line

online

/ˈɒnˌlaɪn/
adjective
1.
of, relating to, or concerned with a peripheral device that is directly connected to and controlled by the central processing unit of a computer
2.
of or relating to the internet: online shopping
3.
occurring as part of, or involving, a continuous sequence of operations, such as a production line
adverb
4.
while connected to a computer or the internet
See offline
Word Origin and History for on-line

online

adj.

in reference to computers, "directly connected to a peripheral device," 1950 (originally as on-line).

on-line in Science
online
  (ŏn'līn')   
Connected to or accessible by means of a computer or computer network.
on-line in Culture

online definition


A term referring to locations on or use of the Internet. The term can be used to refer to a specific location or Web page (“Our sales catalogues can be found online at — ”) or to a personal activity (“I went online to find the information you wanted.”)

on-line in Technology

jargon
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 (or terminal), 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)