I know it must have been hard to go two weeks without a new etymology post, but don’t worry. It’s over now.
Grade showed up relatively recently, first in the early sixteenth century as a noun that had to do with the level/angle of something. Then in the mid seventeenth century, it morphed from that to a verb which meant “to arrange in grades (i.e. levels)”, which is why in the early nineteenth century it turned into “class of things having the same quality or value”. That then morphed into a division of a school curriculum, which may have then turned into the grade a student receives on a piece of work. Meanwhile, the original grade morphed into being just the angle of a road, which is barely used today. Funny what sticks and what doesn’t.
But there’s more to the history. The original grade comes from the modern French grade, which means…grade. Look, they can’t all be huge changes. That grade comes from the classical Latin gradus, which means steps or levels, which comes from gradi, stride and gressus, step or walking. That word in turn comes from the Proto Indo European ghredh, to walk. So, grade is step, in pretty much every definition of the word.
That step/walk definition is present in all the other permutations of the word. Degrade (which actually showed up way before grade, in the late fourteenth century), comes from the Old French degrader, degrade, a mix of the prefix dis-, down, and gradus, step. So you’re stepping down someone. Yeah, I see it.
The other grade words aren’t very complex either. Upgrade, which showed up in 1847, is up + grade—step up. Ditto with downgrade—although that originally meant downward slope, something actually still in use. Then the retro- in retrograde means backwards, which is why retrograde tends to refer to things moving back the way they came.
What’s really interesting is all the other places grade has showed up that you might not be aware of. Graduation? From gradus. Gradient? Probably related (but maybe not). Degree? Yep, that’s in there too. Regress? Digress? Progress? All are from gradus. So someday I’ll have to etymologize all the -gress words now, too.
SourcesUniversity of Texas at San Antonio’s page on Proto Indo European language