Thanks to Sam Riddleburger for his comment re: words he "skips over" when reading because he doesn't quite know what they mean. Sam's comment provided the inspiration for this post, in which I've researched a few words that have befuddled me in the past, and combined it with my Tools of the Trade feature exploring word origins. (Previous editions of TOTT can be found here.)
"Horripilation" is a great word for us mystery writers ... it basically means "goose bumps"! It comes from the Latin word horrere, meaning "stand on end" and pilus, "hair." The word "horrible" also comes from horrere (and I imagine "horror" must be related as well). So those words actually take their names from the physical reaction people have to them. Pretty cool. Bonus word origin ... the medical term for goose bumps is "cutis anserina." In Latin, cutis means "skin" and anser means "goose." Source: MedTerms.com.
The word "mendacious" first came to my attention two weeks ago, when Australian children's writer Jen McVeity used it during the SCBWI Mid-Atlantic Fall Conference. I had no earthly idea what Jen was talking about, so I wrote the word down and looked it up when I got home. According to Merriam-Webster Online, its definition is: "given to or characterized by deception or falsehood or divergence from absolute truth." According to the Online Etymology Dictionary, it hails from the Latin mendacium, "a lie," related to menda, "fault, defect, carelessness in writing."
"Feckless" is one of those words I've seen in print many times, and while I had some sense of its meaning, I was never quite sure. My husband asked about its meaning a couple of months ago, which finally prompted me to look it up. Someone or something who is feckless is "lacking purpose or vitality; feeble or ineffective; careless and irresponsible." It originates in the Scottish word feck, which is simply a shortened version of the word "effect."