Fixer-Upper

I was reading some history of the Middle Ages, and the word "mendicant" came up in regards to some religious orders (you can get the gist of it here). Well, naturally the first word that came to mind when I thought of "mendicant" was "mendacious", even though they don't have anything to do with one another. I would have looked up their meanings even if I weren't sure that there had to be some relationship between the two, though I did think just that.

"Mendicant" simply means "begging": in the case of those mediaeval friars, it referred to the ones who owned no property (and therefore had no labours to perform) but subsisted on the charity of others. It's from Latin "mendicare", "to beg". "Mendacious", on the other hand, means "lying: untruthful", and it's also from Latin, but from "mendacium", "a falsehood".

Well, that's no help, is it? But just look at them! Obviously there's some deeper relationship, right?

There is. The source of both, though distantly, is Indo-European "mend-", "physical defect". A mendicant was originally someone so physically afflicted that he couldn't work but had to beg for a living: someone mendacious was originally someone who writes or speaks faultily, and later one who exhibits the flaw (not physical, but spiritual) of untruthfulness.

IE "mend-" is also, as you might have gathered, the root of "amend", which is to say the righting or repairing of some fault, and likewise "mend", which, after over three weeks of various winter colds, I am finally on.