"Forty" is the only number which has its letters in alphabetical order. "One" is the only number with its letters in reverse alphabetical order.
"Four" is the only number whose number of letters in the name equals the number.
"Rhythms" is the longest English word without the normal vowels, a, e, i, o, or u.
"Stewardesses" is the longest word that can be typed with only the left hand.
"Tautonyms" are scientific names for which the genus and species are the same.
"Taxi" is spelled exactly the same in English, French, German, Swedish, Portuguese, and Dutch.
Augustus Caesar had achluophobia—the fear of sitting in the dark.
Phobophobia is a fear of fearing.