So yeah, this is amazing. Today's OED word of the day has it's earliest quote dated back to Chaucer in about the year 1395. Now, when I see a date like that I just about give up trying to be able to read the quote itself since English has gone through rather significant changes in the last 700 years or so. It's still fun to try, though. So I'm glancing through this old poem, and I have to stop dead when I come to this word. It is not a "small" word (6 characters), and it is common enough that it should have suffered some real alterations by the centuries between now and then.
Or so I thought.
"Plumage" has remained virtually unchanged since it first showed up on the scene! It meant the same then as it does now, and it was spelled the same way also! In all the OED's quotes for the various centuries between now and then, it's right there just like we expect it.