Q: I hear people use “trepidatious” to mean fearful or anxious, but I can’t find it in my dictionary and my spell-checker tells me it’s wrong. Is “trepidatious” a word?
A: Yes, it’s a word, though it’s more common in the US than in the UK. Six of the 10 standard dictionaries we regularly consult recognize the adjective.
All five American dictionaries include it as standard English. However, it’s found in only one of the five British dictionaries, Lexico (the former Oxford Dictionaries Online), which describes the usage as informal. All 10 dictionaries include the noun “trepidation.”
The Oxford English Dictionary, an etymological dictionary based on historical evidence, defines the adjective as “apprehensive, nervous; filled with trepidation.” The dictionary says it originated with the addition of the suffix “-ious” to either trepidāt-, the past participial stem of the classical Latin verb trepidāre (to be alarmed), or to the root of the English word “trepidation.”
Although the usage is more popular in the US than the UK, the first OED citation is from an early 20th-century British novel about colonial India:
“Hilda looked up from the papers she had been busy with as he entered—in fact, made a guilty and trepidatious attempt at sweeping them out of sight” (The Sirdar’s Oath: A Tale of the Northwest Frontier, 1904, by Bertram Mitford, a member of the aristocratic and literary Mitford family).
The earliest American citation in the OED is from the May 18, 1940, issue of the Circleville Herald, an Ohio newspaper: “A trepidatious Europe today remained tense, worried, fearful, for the outcome of what military men predict will be the greatest battle in the history of the world.”
The much older noun “trepidation” ultimately comes from the Latin trepidāre. When it first appeared in the early 17th century, the OED says, “trepidation” referred to agitation in the scientific sense:
“Massiue bodies … haue certaine trepidations and wauerings before they fixe and settle” (from Of the Proficience and Aduancement of Learning, Diuine and Humane, 1605, by Francis Bacon).
Two decades later, the noun took on its modern sense of “tremulous agitation; confused hurry or alarm; confusion; flurry; perturbation,” according to the dictionary.
The earliest citation is from another work by Bacon: “There vseth to be more trepidation in Court, vpon the first Breaking out of Troubles, then were fit” (The Essayes or Counsels, Ciuill and Morall, 1625).
Some sticklers have objected to the use of the relatively new adjective “trepidatious,” but we see nothing wrong with it. The linguist Arnold Zwicky, who uses the term himself, wrote a strong defense of the adjective in a Nov. 17, 2004, post on the Language Log.
[Note: This post was updated on Feb. 19, 2020, to reflect newer dictionary information. Posts on “trepidatious,” “trepidant,” and “trepidated” also appeared in 2015 and 2017. ]