Learn English – Which is correct, “on-line” or “online”

adverbsamerican-englishhyphenationopen-vs-closed-vs-hyphenatedorthography

I am still seeing uses of on-line, though I think it is incorrect. For example:

A web browser enables a user to go on-line/online.

Can you tell me which is the more appropriate to use, on-line or online?

Best Answer

According to this Google Ngram, online is used more often.

The use has shifted over time to omit the hyphen. For example in 1950, the OED writes:

1950 W. W. Stifler High-speed Computing Devices (Engin. Res. Associates) ii. 7 In on-line operation the input is communicated directly‚Ä•to the data-reduction device.

This was still the case in the 1970s:

1971 Computers & Humanities 5 192 The shoebox is an automatic text-processing and retrieval system implemented for on-line operation on an ibm 360/50 computer.

However, now the hyphen has dropped out, so the usage is as follows:

1998 T. Sheldon Encycl. Networking (new ed.) 990 In online transaction processing, transactions are executed immediately, as opposed to batch processing.

So, the current usage favors online instead of on-line.