A. Shah Idil*
I was perusing through Brown’s 1998 revision of the epilepsy needs document for the UK  when I came across on page 439 a word unfamiliar to my engineer’s eyes: “armentarium”.
I asked the Oxford English dictionary to define the word for me, and it returned to my surprise: “no exact matches”. It did however suggest an alternative with two extra letters: “armamentarium” (from the Latin armāmentum – “arsenal”). This had the meaning: “the medicines, equipment, and techniques available to a medical practitioner” – much more in line with a paragraph regarding new trends in anti-epileptics.
I thought perhaps Brown had made a simple mistake, but a quick search on PubMed delivered 113 articles with the same non-word. Google Scholar gave me 2,390! There have already been a few papers published in 2019 containing “armentarium”, with phrases such as “the therapeutic armentarium”, and “the interventionalists’ armentarium” abound –. If one goes back far enough, we can even find 5 papers with the typographical error in the title itself –!
I believe the error started from one of these five, specifically with Fox’s 1968 paper, with not just one, but two typographical errors in the title: “Endodontic armentarium for the genral practitioner”. I cannot find the full paper, or even an abstract, so I cannot say if he struggled with spelling or had a particularly poor editor. From there, the error probably propagated.
After a brief investigation I found that there is indeed such a word as “armentarium” – just not in English. It is the accusative singular of the Latin word armentarius, meaning a herdsman, or a cowboy .
So, let us then all not be “cowboys” and allow ourselves to engage in the proliferation of incorrect terminology.
*A. Shah Idil (corresponding author, email: firstname.lastname@example.org) is with the Implanted Devices Group, University College London, London, UK.