More etymology of English words - stave off, deadlock, desultory, ludicrous, etc.

Here's a short piece from courant.com with some etymology of some words you might or might not have known. On the word desultory:

You probably wouldn't associate "desultory," meaning "haphazard, random, having no set plan," with athletics. But, in fact, the term was first used to describe skilled Roman horsemen who were capable of leaping from one mount to another. These equestrian acrobats were called "desultors," from the Latin "de-" and "salto" (to leap), and so "desultory" came to mean "moving from one thing to another."