Palindrome

A palindrome is a word, phrase, number or any other sequence of units (like a thread of DNA) which has the property of reading the same in either direction (the adjustment of spaces between letters is generally permitted). The word palindrome comes from the Greek words palin (back) and dramein (to run) meaning running back. Writing literature in palindromes is an example of constrained writing.

According to Bill Bryson's Mother Tongue: English & How It Got That Way (p. 227): "Palindromes... are at least 2,000 years old. The ancient Greeks often put 'Nipson anomémata mé monan opsin' on fountains. It translates as 'Wash the sin as well as the face.' The Romans admired them, too, as demonstrated by 'In girum imus nocte et consumimur igni' ('We enter the circle after dark and are consumed by fire'), which was said to describe the action of moths."

Palindromes occur in many languages, but they are particularly prevalent in English due to the wide variety and frequent reversal of letter pairs within words.

Examples of palindromic words and phrases:

Symmetry by the letters

Aibohphobia, the fear of palindromes, is itself a palindrome
ABBA
radar (acronym from RAdio Detection And Ranging, so it's self-defining too.)
Glenelg (place name in Scotland and Australia)
Live Evil (used as an album title by, amongst others, the metal band Black Sabbath and jazz trumpeter Miles Davis)
redivider (the longest 'natural' palindrome in English)
Madam, I'm Adam.
Do geese see God?
Dennis sinned.
Koselure Mordni La Palindrome rules - OK
God hexes sex, eh dog? (written by Kingturtle)
Naomi did I moan?
Sex at noon taxes.
Able was I, ere I saw Elba. (the famous 'Napoleon's Lament', source unknown)
Ten animals I slam in a net.
Was it Eliot's toilet I saw? (Bill Bryson)
A Man, a plan, a canal - Panama! (Leigh Mercer)
- A man, a plan, a canoe, pasta, heros, rajahs, a coloratura, maps, snipe, percale, macaroni, a gag, a banana bag, a tan, a tag, a banana bag again, or: a camel, a crepe, pins, spam, a rut, a Rolo, cash, a jar, sore hats, a peon, a canal -- Panama! (attributed to Guy Steele)
Too far, Edna, we wander afoot. (Bill Bryson)
Yawn! Madonna fan? No damn way!
Tarzan raised a Desi Arnaz rat. (Baby Gramps)
Norma is as selfless as I am, Ron. (W. H. Auden)
Go hang a Salami. I'm a Lasagna Hog. (Baby Gramps)
Sums are not set as a test on Erasmus. (W. H. Auden)
Satan, oscillate my metallic sonatas. (Stephen Fry)
No, it is opposed, art sees trades opposition. (W. H. Auden,on a discussion of photography vs. painting)
Straw? No, too stupid a fad. I put soot on warts. (Leigh Mercer)
No, son, onanism's a gross orgasm sin: a no-no, son.
Are we not drawn onward, we few, drawn onward to new era? (Bill Bryson)
Rettebs, I flahd noces, eh? Ttu, but the second half is better. (Stephen Fry)
Doc, note, I dissent. A fast never prevents a fatness. I diet on cod. (Peter Hilton)
"It's Ade, Cilla, Sue, Dame Vita, Edna, Nino, Emo! Come on in and eat, I've made us all iced asti." (Stephen Fry)
"Peel's foe (not a set animal) laminates a tone of sleep." (Lyrics from Kew Rhone)
"Lewd did I live, & evil I did dwel." (John Taylor, the Water Poet)

In Dutch:

parterretrap: "stairway to the ground floor"
nepparterreserretrappen (less serious extension of the previous): "fake stairways from the ground floor to the sun lounge"

In Estonian:

Aias sadas saia: "It rains white bread in the garden."

In Finnish there are two 25-letter palindromes:

Solutomaattimittaamotulos: "the result from a measurement laboratory for tomatoes"
saippuakuppinippukauppias: "soap cup trader"

In French:

kayak
élu par cette crapule
la mariée ira mal
Laval

In Hungarian:

Géza, kék az ég: "Géza, the sky is blue."
Rám német nem lel, elmentem én már: "The germans won't find me, I'm already gone." (1943)
Indul a görög aludni: "The greek goes to sleep."
Rémes tóga bagót sem ér: "Crap chiton worths nothing."
Erőszakos kannak sok a szőre: "Agressive males have lots of hair."
Keresik a tavat a kis erek: "Small streams look for the lake."
Kis erek mentén, láp sík ölén odavan a bánya rabja: jaj, Baranyában a vadon élő Kis Pálnét nem keresik!: "Along the small streams and in the flat lap of the moorland gone the prisoner of the mine: oh, nobody looks for Ms. Kis Pál who lived in the woods of Baranya." (Created by Demők Béla.)

In Mandarin Chinese:

Source: 回文遊戲 (Palindrome Games)

Shanghai zilaishui lai zi hai shang (上海自來水來自海上 in pinyin: shang4 hai3 zi4 lai2 shui3 lai2 zi4 hai3 shang4): "Shanghai's running water comes from the sea"
Zhongguo Shan zhong you Zhongshan Guozhong (中國山中有中山國中 zhong1 guo2 shan1 zhong1 you3 zhong1 guo2 zhong1): "In the Chinese Mountain, there is Central-Mountain Middle School"; alternate translation: "In between the Chinese mountains, there is Dr. Sun Yat-sen Middle School"
Hualian Yinshuachang shuayin lianhua (花蓮印刷廠刷印蓮花 hua1 lian2 yin4 shua1 chang3 shua1 yin4 lian2 hua1): "Hualien Press prints lotuses"
chuan shang nüzi jiao zinü shang chuan (船上女子叫子女上船 chuan2 shang4 nü3 zi3 jiao3 zi3 nü3 shang4 chuan2): "The woman on the boat is calling her children to go onboard"
tian shang long juan feng juan long shang tian (天上龍捲風捲龍上天 tian1 shang4 long2 juan3 long2 shang4 tian1): "The dragon up on the sky whirls a wind to roll a dragon up to the sky"

In Slovene:

Perica reže raci rep: "Laundress cuts duck's tail."

In Norwegian:

Regninger: The longest palindrome norwegian word. Means "bills".

Most of us have two palindromic years 1991 and 2002 in our lifetimes. Furthermore, both these years have identical calendars. Even Easter is on the same day. The next palindromic year will start on a Friday

Japanese palindromes rely on the hiragana syllabary, like the word "shinbunshi" (newsprint). Their syllabary makes it possible to make very long palindromes. For more information, see kaibun (回文).

Symmetry by the words

Some palindromes use words as units rather than letters. They Might Be Giants released a single called I Palindrome I, the lyrics of which include the word palindrome: "Son I am able," she said, "though you scare me." "Watch," said I, "beloved," I said, "watch me scare you though." Said she, "able am I, Son."

Another example:

You can cage a swallow, can't you, but you can't swallow a cage, can you?

Symmetry by the lines

Still other palindromes take the line as the unit. The poem Doppleganger was composed by James A. Lindon.

Doppelganger

Entering the lonely house with my wife

I saw him for the first time

Peering furtively from behind a bush --

Blackness that moved,

A shape amid the shadows,

A momentary glimpse of gleaming eyes

Revealed in the ragged moon.

A closer look (he seemed to turn) might have

Put him to flight forever --

I dared not

(For reasons that I failed to understand),

Though I knew I should act at once.

I puzzled over it, hiding alone,

Watching the woman as she neared the gate.

He came, and I saw him crouching

Night after night.

Night after night

He came, and I saw him crouching,

Watching the woman as she neared the gate.

I puzzled over it, hiding alone --

Though I knew I should act at once,

For reasons that I failed to understand

I dared not

Put him to flight forever.

A closer look (he seemed to turn) might have

Revealed in the ragged moon.

A momentary glimpse of gleaming eyes

A shape amid the shadows,

Blackness that moved.

Peering furtively from behind a bush,

I saw him for the first time,

Entering the lonely house with my wife.

Symmetry by sound

The Islandic music-band Sigur Rós composed a song on their album Ágætis Byrjun, which partly sounds the same, playing forwards or backwards. Not only symmetric from the notes, but also symmetric in the sound by mixing the reverse music over the original. The song - named Staralfur - can be downloaded at their website under http://www.sigur-ros.co.uk/media/index.html

See also crab canon, in classical music: a canon in which one line of the melody is reversed in time and pitch from the other.

In genetics, a palindromic DNA sequence can form a hairpin.