The University of Oregon follows spelling and usage conventions in The American Heritage Dictionary of the English Language.

Use the first spelling listed, never the variant, except in official titles or proper names. If a compound noun isn’t listed as one word, use two.

acknowledgment [not acknowledgement]
catalog [not catalogue]
course work [not coursework]
fieldwork [not field work]
flier [‘a paper handout’ or ‘a person who flies,’ not flyer]
fundraising [not fund-raising]
grassroots [not grass-roots]
gray [not grey]
Hawaii [not Hawai’i ]
judgment [not judgement]
percent [not per cent]
theater [not theatre]
toward [not towards]

In the case of theater vs. theatre, we allow exceptions only in the listing of the names of buildings or academic units that use the variant spelling.

Robinson Theatre, University Theatre, James F. Miller Theatre Complex, Department of Theatre Arts

Accents or hyphens are sometimes essential for spelling or pronouncing a word correctly. See also Diacritical Marks under Punctuation.

café, cliché
co-op (short for ‘cooperative housing’) vs. coop (where a chicken lives)
résumé (noun) vs. resume (verb)

Spell Checkers

Although spell-checking programs can help you locate errors in electronic manuscripts, you can’t rely on them as a substitute for your eyes and brain. Many spell checkers can’t, for example, choose preferred spellings, verify the spelling of proper nouns, recognize technical terms, pick out contextual errors such as dreadlocks for deadlocks, or distinguish among homonyms such as their, there, and they’re. Use them with caution.