The combination "ough" can be pronounced in nine different ways. The following sentence contains them all: "A rough-coated, dough-faced, thoughtful ploughman strode through the streets of Scarborough; after falling into a slough, he coughed and hiccoughed."
The verb "cleave" is the only English word with two synonyms which are antonyms of each other: adhere and separate.
The only 15 letter word that can be spelled without repeating a letter is uncopyrightable.
Facetious, and abstemious and arsenious contain all the vowels in the correct order.