Editorial Style Guide

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(Laurie Smith-Frailey)

[ O ]

off campus, off-campus; on campus, on-campus

Hyphenate as an adjective before a noun; otherwise, leave open.

  • There’s even an on-campus post office in Stratton Student Center!
  • Sarah told her roommate she’d be spending the night off campus, but she didn’t specify where.

on site, on-site

See off campus, off-campus; on campus, on-campus (above).

offline (adj. or adv.)

As an adjective, means not connected to a computer or network, although metaphorically can also mean at a later (or different) time or place (an adverb in such a case).


See fractions.


online (adj.)

Online is the spelling accepted by The New York Public Library Writer’s Guide to Style and Usage and many Web style guides. Do not hyphenate. Means connected to a computer network, or at least accessible by a computer with network access.

open source (adj.)

Means of or relating to source code that is available to the public. No hyphen.

open-ended (adj.)

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OpenCourseWare, OCW

These terms are out of date! Under efforts to brand OCW as an MIT activity, OCW or OpenCourseWare should henceforth be referred to as MIT OpenCourseWare (first reference) or MIT OCW (subsequent reference). See also opencourseware (below).


Generic name for the open sharing movement, led and fostered by MIT through the MIT OpenCourseWare initiative, that encourages other institutions to openly share their educational materials freely on the Internet—similar to MIT OCW.

oral, verbal

See Troublesome pairs.

ordinal number

Refers to a number that designates place in an ordered sequence.See also numbers and numerals.

  • Spot won 2nd Place Overall in the annual dog show last year.
  • Susan Hockfield is the 16th president of MIT.

over, more than

See Troublesome pairs.

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Massachusetts Institute of Technology

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