The words “racecar” and “kayak” are the same whether they are read left to right or right to left.
A snail can sleep for 3 years.
A duck’s quack doesn’t echo, and no one knows why.
The combination “ough” can be pronounced in nine different ways. The following sentence contains them all: “A rough-coated, dough-faced, thoughtful plough man 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.