Predominantly or predominately?

A while back I was editing an article and came across a sentence like “The community is predominately white.” It took me till the second read to notice that “predominately” wasn’t “predominantly.” And I was pretty proud of myself when I caught this “error.” But luckily I wasn’t so cocky as to trust my own judgment. I looked them up.

It turns out that “predominately” and “predominantly” are both legitimate. And if there’s a difference between them, it’s very subtle. This is from "Webster's New World College Dictionary":

predominate: 1. to have ascendancy, authority, or dominating influence (over others); hold sway 2. to be dominant in amount, number, etc.; prevail; preponderate. Related forms: predominately: adverb

predominant: 1. having ascendancy, authority, or dominating influence over others; superior 2. most frequent, noticeable, etc.; prevailing; preponderant. Related forms: predominantly: adverb

“Merriam-Webster’s Dictionary of English Usage” argues that the words are basically synonyms. So how do you know which one to choose?

Well, if you want to follow someone else’s lead, you could do worse than to take the "Associated Press Stylebook’s" advice:

"predominant, predominantly: Use these primary spellings listed in 'Webster's New World' for the adjectival and adverbial forms. Do not use the alternatives it records, 'predominate' and 'predominately.' The verb form, however, is 'predominate.'"

Plus, Merriam-Webster's usage guide calls “predominately” a “less frequently used alternative” to predominantly. So that could be construed as yet another reason to stick with “predominantly.”

Of course, follow their cue only if you want to march in step with the majority. If you march to the beat of your own drummer, “predominately” is valid, too. It's just not predominant.