I would say both are acceptable, but prefer cooperative without the hyphen myself. I am Scottish, by the way. However, my Word spell-checker for British English insists I put a hyphen in. Here are a few references from various sources. Interestingly enough, the Guardian (a UK newspaper) style guide advises writers to use cooperative WITHOUT the hyphen.
Hope this helps anyway!
US Style Guide
"Co-op" is acceptable as an abbreviation, but remember, it's "cooperative" without a hyphen. " The Office of Cooperative Education and Career Services" should always be spelled out.
The UFCN Writing Stylebook
Compiled for the
University of Florida Communications Network
Office of News & Public Affairs.
Updated on 08/24/00
co- -- Retain the hyphen when forming nouns, adjectives and verbs that indicate occupation or status:
* co-respondent (in a divorce suit)
(Several are exceptions to Webster's New World in the interests of consistency.) Use no hyphen in other combinations:
Cooperate, coordinate and related words are exceptions to the rule that a hyphen is used if a prefix ends in a vowel and the word that follows begins with the same vowel.
cooperate, cooperative, cooperation
no hyphen, but the store is the Co-op
CONTENTS · BIBLIOGRAPHIC RECORD
Kenneth G. Wilson (1923–). The Columbia Guide to Standard American English. 1993.
Three usage questions frequently arise: (1) Does co- mean “equal to” or “subordinate to” when it occurs with words such as coworker and copilot? Answer: it means either and both, and the referents and context will control. A coworker usually is neither subordinate nor superior to a fellow worker, but the copilot is always subordinate to the pilot. (2) Do newly created words using the prefix always begin as slang, or are words such as cohost and co-agent Standard from the start? Answer: such words, and nonce words using the co- prefix as well, are usually Standard almost at once, so long as the concept is clear: for example, sled-dog drivers and their codrivers are probably in the same relationship to their enterprise as pilot and copilot are to theirs: one is captain and in overall charge, and the other is the mate; and only one can actually be at the controls at any given time. (3) How should the co- prefix be attached to the base word, with a hyphen or without? Answer: usually without a space or hyphen (coincidence, coordinate), but occasionally when the base word begins with o (co-opt, co-own—but see also DIERESIS) or when a word is so new as to look odd and risk misreading without a hyphen (co-anchor or co-belligerent), a hyphen will help. The prefix co- means “together, joint,” as in co-owner; “equally, mutually,” as in coextensive, cooperative; “partner with, associate to,” as in coauthor, coproducer, or to cosign [a note]; and “assistant or subordinate to,” as in coadjutor. And sometimes the “equal or subordinate” issue is ambiguous, as in cohost, coanchor. (There are also mathematical senses meaning “complement,” as in cosine, cotangent.) Three other forms occur: col- (before l, as in collaborate); com- (before b, p, and m, as in combine, companion, and commiserate); and con- (before other sounds, as in contaminate). 1
| Sheila Hardie|
Local time: 07:37
Native speaker of: English
PRO pts in pair: 679