Dictionary.com
Thesaurus.com

online

American  
[on-lahyn, awn-] / ˈɒnˈlaɪn, ˈɔn- /
Or on-line,

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 relating 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

  1. with or through a computer, especially over a network.

online British  
/ 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

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

adverb

  1. while connected to a computer or the internet

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
online Scientific  
/ ŏnlīn /
  1. Connected to or accessible by means of a computer or computer network.


online Cultural  
  1. 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.”)


Etymology

Origin of online

First recorded in 1915–20 (in sense “located on rail lines”); 1945–50 for other senses

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

“At first I thought it was just me, but then I went online and saw that it’s happening to so many people,” Roller said.

From Los Angeles Times

Californians can instead fill out one form on the state’s online Delete Request and Opt-out Platform, also known as DROP, to request that all registered data brokers scrub their personal information.

From Los Angeles Times

Hilton on Tuesday took the relatively rare step of removing a hotel from its system in the midst of criticism online over the property’s refusal to house Immigration and Customs Enforcement officers coming to Minneapolis.

From The Wall Street Journal

It is not the first time Lego has dabbled in digital experimentation or sought to appeal to increasingly online audiences.

From BBC

That was enough for the army of online "Swifties", who scrutinise the singer's every move, to identify "Taylor's wine".

From Barron's