Some trips to the library are more helpful than are others. I wrote on 2/19/2002 about AOL’s use of “Online,” pronounced “on´-line” in its television ads. I finally got to the Mt. Lebanon Public Library yesterday to check this usage in the Oxford English Dictionary (OED). What I found was in the Volume III Supplement of 1982.
I am reluctant to trust a 20-year-old reference as a guide to current computer jargon, but I take some comfort in the absence of “online” (one word) in the OED. (The Encarta World English Dictionary of 1999 does recognize both “online” and “on-line,” but it offers neither a pronunciation guide nor derivation. I find it difficult to take this book seriously.) The OED describes the stress of “on-line” as “variable,” and in no case, where a stress pattern was indicated, was the first syllable stressed to the degree that it is in the AOL ads.
My speculations about the origin of “on-line” appear to have been off the mark. The OED offers various definitions for both “on-line” and “off-line” as adjectives and adverbs—the latter term seemingly the older by a few decades. The earliest reference was from 1926 (“off-line offices”) in the sense of not situated or performed by railway or by rail. No analogous use was noted for “on-line,” although, as I mentioned in my earlier note, the term is certainly used that way (as in “on-line industries”) and has been for some time. The OED did acknowledge a similar sense in relation to airlines, but the earliest meaning cited for “on-line” was indeed in a computing context, referring to peripherals directly connected to a computer. Amazingly, this appeared in a book, High-speed Computing Devices, edited by W.W. Stifler, Jr., and assembled originally as a report for the Office of Naval Research in 1950. The usage that I thought might be oldest, having the same meaning as “on stream” (no hyphen), as in “the plant came on line” (also no hyphen), was represented by a 1968 reference, although “on stream” itself dates from at least 1930.