Words whose meanings contradict one another:

• BILL (“monetary note” and “statement of debt”)
• BUCKLE (“to secure” and “to collapse”)
• CLEAVE (“to separate” and “to bring together”)
• DOWNHILL (“progressively easier” and “progressively worse”)
• DUST (“to add dust” and “to remove dust”)
• FAST (“quick-moving” and “immobile”)
• GARNISH (“to add to” and “to take from”)
• MODEL (“archetype” and “copy”)
• OVERSIGHT (“attention” and “inattention”)
• PEER (“noble” and “person of equal rank”)
• PUZZLE (“to pose a problem” and “to try to solve a problem”)
• SANCTION (“to permit” and “to restrict”)

And TABLE means both “to present for consideration” and “to remove from consideration.”

This is a grammatically valid English sentence:

Buffalo buffalo Buffalo buffalo buffalo buffalo Buffalo buffalo.

It was discovered/invented in 1972 by University of Buffalo linguist William J. Rapaport. It means “Buffalo from the city of Buffalo that are intimidated by other buffalo from the city of Buffalo themselves intimidate a third group of buffalo, also from Buffalo.”

Is that clear? Be glad you’re not in the Netherlands, where Als In Bergen, bergen bergen bergen bergen bergen bergen bergen bergen bergen bergen means “If in Bergen, heaps of mountains salvage heaps of mountains, then heaps of mountains salvage heaps of mountains.”

hieromachy
a fight or quarrel between priests

A capitonym is a word that changes meaning when it’s capitalized:

A herb store owner, name of Herb,
Moved to a rainier Mount Rainier.
It would have been so nice in Nice,
And even tangier in Tangier.

An isogram is a word in which no letter is repeated:

• METALWORKINGS
• LEXICOGRAPHY
• MALNOURISHED
• THUNDERCLAPS
• UNFORGIVABLE
• AMBIDEXTROUSLY
• UNCOPYRIGHTABLE

Theoretically the limit is 26 letters, but that’s an Everest that no one has scaled. Dmitri Borgmann has conquered some lesser peaks with THUMBSCREW-JAPINGLY (18 letters, “as if mocking a thumbscrew”) and PUBVEXINGFJORD-SCHMALTZY (23 letters, “as if in the manner of the extreme sentimentalism generated in some individuals by the sight of a majestic fjord, which sentimentalism is annoying to the clientele of an English inn”). Maybe what we lack is imagination.

The most frequently used letters of the English alphabet, in order, are ETAOIN SHRDLU.

They can be rearranged to spell SOUTH IRELAND.

griffade
sudden seizure with the claws

whiskerine
n. beard-growing contest