Subalphabetic Words

It is harder to make long words from the second half of the alphabet, as there are only two vowels, and these vowels are less common than those found in the first half of the alphabet. The longest is NONSUPPORTS (11 letters), although if place names are allowed then the 13-letter words TUTTOQQORTOOQ (in Greenland) and ROSSOUWSPOORT (in South Africa) are valid.

ACCEDED, CABBAGE, BAGGAGE, DEFACED, EFFACED, and FEEDBAG are seven-letter words which can be played on a musical instrument, that is to say they contain only letters in the range A-G. CABBAGED, at eight letters, is the longest such word.

Symmetrical Words Closely related to palindromes, symmetrical words are words that have an axis of symmetry, or point of rotational symmetry. Needless to say, it is relevant whether the word is written in upper or lower case.

Some long words with horizontal symmetry are: BEDECKED, BOOHOOED, CHECKBOOK, CODEBOOK, COOKBOOK, DECIDED, DIOXIDE, DOBCHICK, EXCEEDED, HOODOOED, and KEBOBBED. The longest such word, with ten letters, is OKEECHOBEE.

The longest words with vertical symmetry are OTTO, MAAM, and TOOT. Others include MOM, WOW, AHA, AHA, AIA, AMA, AVA, AWA, HAH, HOH, HUH, MAM, MIM, MUM, OHO, OXO, TAT, TIT, TOT, TUT, UTU, VAV, and WAW!

When written in upper case, the word BID has horizontal symmetry, but when written in lower case it has vertical symmetry – bid!

SWIMS is probably the longest word with 180-degree rotational symmetry. All of the letters in the words SOONISH (7 letters) and ONIONS (6 letters) independently have 180-degree rotational symmetry.