Q: My wife and I were watching a broadcast of the pairs figure skating in Vancouver when I caught what I consider two misuses of the word “unison”: “They were completely unison” and “They were out of unison.” Do you agree?
A: In music, the noun “unison” refers to two or more notes of the same pitch (or, loosely, one or more octaves apart). The word, which entered English in the 16th century, ultimately comes from the Latin unus (one) and sonus (sound), according to the Oxford English Dictionary.
However, the word ”unison” has been used figuratively since the 17th century to refer to perfect agreement or concord or harmony, especially in the phrase “in unison.”
So is “unison” being used correctly in the two sentences you mention?
In the first one (“They were completely unison”) the word is an adjective. Although “unison” has been used adjectivally at times, the OED says this usage is now considered obsolete. The correct sentence: “They were in unison” or (with a bit of redundancy for emphasis) “They were in perfect unison.”
We see nothing wrong with the second sentence (“They were out of unison”). We can’t find any published references to “out of unison” in the OED , but it strikes us as an acceptable way of describing the opposite of “in unison.”