It was Samuel Goldwyn, the film producer, who said that a verbal contract isn’t worth the paper it’s written on. This witticism depends on our understanding the word verbal as equivalent to oral (or spoken).
But is it? The most traditional meaning of verbal is “having to do with words.” If that’s so, then even written contracts are verbal in nature. Hence nonverbal means “involving no use of language—or at least minimal use of it.” It certainly isn’t equivalent to written.
According to the spanking-new Garner’s Modern English Usage (5th ed. 2023), the use of verbal to mean oral isn’t above reproach. It’s a Stage 4 misusage on Garner’s Language-Change Index, meaning it’s not quite into the realm of full acceptability: “In recent years, some people have said that they feel awkward using oral because of prurient connotations; that is, the word seems most often to appear in reference to oral sex.” This association, however, is overstated: “Why this should be so is hard to fathom, since we have oral surgery and oral reports, not to speak of oral commitments and oral communication. If you think of oral in a narrow sexual sense, you should wash your mouth out with soap. Otherwise, we may be in danger of losing a perfectly good word.” (P. 1139.)
Then again, any usage that progresses to Stage 4 on the Language-Change Index is almost certain, in time, to make it to Stage 5 (full acceptability by editorial standards). For now, though, it’s recommended that you use oral for things spoken, and verbal for things put into words.
And if you don’t yet have the massively revised 5th edition of Garner’s Modern English Usage—with more than a thousand new entries—we suggest that you hasten to order it here.