For a rather unusual reason, I've been reading a lot of Edgar Allan Poe lately and can't help but notice the plethora of words that many probably don't recognize. Maybe I'm being paranoid (as with "sagacious), but I just feel the need to share some definitions here.
Long story short, this is less a traditional "Grammar War" entry and more just a list of uncommon words that were apparently beloved by the great Poe.
beetling - to scurry like a beetle
ephemeron - something short-lived or of no lasting significance
habiliments - the dress characteristic of an occupation or occasion - usually used in plural
ineffable - incapable of being expressed in words
lustrum - a period of five years (the Roman census)
mummer - a performer in pantomime
pertinacity - adhering resolutely to an opinion, purpose, or design (perversely pertinent; stubbornly tenacious)
sagacious - keen in sense perception
tinctured - to tint or stain with a color; to instill or infuse with a property or entity
And, for a bonus word, a word I learned from Mr. Alan Burnett (and not from Poe):
cordwainer - shoemaker