The wordplay glossary.

A word that becomes a different word, with a different meaning, when its letters are reversed. Examples: stop/pots, evil/live, desserts/stressed. Coined in 2017 by Levi Budd, from his first name + the -drome of palindrome. The subject of this entire site — start with the dictionary of pairs.

A word, phrase, or sequence that reads the same forwards and backwards. Examples: noon, kayak, racecar; the sentence 'A man, a plan, a canal — Panama!' From Greek palindromos, 'running back again'. Palindromes survive reversal unchanged; levidromes are changed by it. See our palindrome lists and the Journal's history of palindromes.

The older technical name for a levidrome — a word that spells a different word backwards. The term is itself a joke: it is 'palindromes' spelled backwards. It appears in word-game literature from the mid-twentieth century onward. Same pattern as a levidrome; the newer word is simply friendlier, and it comes with a better story.

Another specialist synonym for a reversal pair, used by some linguists and crossword constructors. If you meet levidrome, semordnilap, and anadrome in the wild, they are three labels for one phenomenon: two words that are mirror spellings of each other.

A word or phrase formed by rearranging the letters of another, in any order. Examples: listen/silent, astronomer/moon starer. Every levidrome is an anagram of its partner, but only the perfect mirror-reversal anagrams count as levidromes. From Greek ana- (back, again) + gramma (letter).

A piece of writing designed to be read as a different (or the same) word when viewed from another angle — most often rotated 180 degrees or reflected in a mirror. Ambigrams are calligraphy and design rather than spelling patterns; the artist John Langdon and the writer Douglas Hofstadter popularised them, and Dan Brown's novels carried them to a mass audience. A levidrome works in plain text; an ambigram needs the artwork.

A sentence that uses every letter of the alphabet at least once. Example: 'The quick brown fox jumps over the lazy dog' — 35 letters, all 26 covered. Pangrams are used to display typefaces and test keyboards. A 'perfect pangram' uses each letter exactly once and is correspondingly hard to write without abbreviations or names.

A word in which no letter repeats — or, in a stricter sense, in which every letter appears the same number of times. Examples: background, downstream, and uncopyrightable, often cited as the longest common example at 15 letters. Isograms are beloved by puzzle setters because their letter patterns are so distinctive.

A word in which no letter repeats — in practice, a synonym for the strict form of isogram. Some writers reserve heterogram for phrases and sentences with no repeated letters. Either way, it is the opposite pole from a palindrome: maximum variety instead of perfect symmetry.

A piece of writing that deliberately omits a letter — most famously the letter E, the commonest letter in English. Ernest Vincent Wright's 1939 novel Gadsby runs some 50,000 words without one, and Georges Perec's French novel La Disparition (1969) does the same and was translated into English, still without E, as A Void. A levidrome is found; a lipogram is willed into existence by discipline.

A word made of the same part repeated: bye-bye, so-so, papa. In biology, a tautonym is a species name in which genus and species are identical, such as Gorilla gorilla. Repetition, not reversal — but collectors of word patterns usually end up keeping a list of these too.

A word or text that uses only one vowel. Examples: strengths uses only E; Perec (again) wrote a univocalic novel using only E, then another using only A. Univocalics are the vowel counterpart of lipograms: constraint as a creative engine.

The plain descriptive term for two words that are exact mirror spellings of each other — in other words, a levidrome pair described without using any coined term at all. Crossword dictionaries and word lists often file them under this heading, or simply mark a word '(rev.)' to note that it reverses into another entry.

A grid of words that read the same across and down, row matching column. The ancient Sator Square (SATOR / AREPO / TENET / OPERA / ROTAS) is also fully palindromic, which is why it opens our Journal's history of palindromes. Word squares are the two-dimensional cousins of both palindromes and levidromes.