Illegitimi non carborundum is a mock-Latin aphorism meaning "Don't let the bastards grind you down".
The word illegitimi (i.e., the plural of illegitimus, actually translates to "unlawful" or "outlaw" but resembles the English "illegitimate") is sometimes given in the plural dative case (that is, illegitimīs), a case that follows the Latin gerundive and denotes agency. Non negates activity. Carborundum is an industrial abrasive material also known as silicon carbide, but its name resembles a Latin gerundive, a grammatical construct that expresses desirability of whatever the verb denotes. So carborundum can be mock-translated to mean "fit to be ground". Thus "illegitimi[s] non carborundum" would mean "not fit to be ground by the illegitimate", or "Don't let the bastards grind you down".
The phrase originated during World War II. Lexicographer Eric Partridge attributes it to British army intelligence very early in the war (using the plural dative/ablative illegitimis). The phrase was adopted by US Army General "Vinegar" Joe Stillwell as his motto during the war. It was later further popularized in the US by 1964 presidential candidate Barry Goldwater.
The phrase is also used as the first line of one of the extra cod Latin verses added in 1953 to an unofficial school song at Harvard University: Ten Thousand Men of Harvard. This, the most frequently played Fight song of the Harvard Marching Band, is, to some extent, a parody of more solemn school songs like "Fair Harvard thy sons to your Jubilee throng" etc. The first verse goes:
Illegitimum non carborundum;Domine salvum fac.Illegitimum non carborundum;Domine salvum fac.Gaudeamus igitur!Veritas non sequitur?Illegitimum non carborundum—ipso facto!The phrase is also used as part of a student painted crest on the bottom floor of Hodge Hall at Princeton Theological Seminary.
A wooden plaque bearing the phrase sat prominently on the desk of former Speaker of the U.S. House of Representatives John Boehner.
There are many variants of the phrase, such as
Non illegitimae carborundumNoli illegitimi carborundumNil illegitimi carborundumNon illegitimis carborundumIllegitimi nil carborundum - echoing the Latin tag nil desperandum ('never despair', 'don't give up')Nil bastardo carborundumNolite te bastardes carborundorumNil carborundum ab illegitimatiIllegitimis non carborundumNil illegitimo in desperandum carborundumNil carborundum illegitamaeNec Illegitimi carborundumNolite Illegitimos Conterere VosNon carborundum bastardumNihil est in carborundum, illegitimaeNone of these variants is 'legitimate' Latin any more than the original. Carborundum is a noun and not a gerundive of any verb (although it does look like a gerundive). Also 'bastard' in Latin is spurius (another Latin word for bastard is nothus, but it is very uncommon). The two most common variations translate as follows: illegitimi non carborundum = the unlawful are not silicon carbide, illegitimis non carborundum = the unlawful don't have silicon carbide.
"Bastards" is often used in English as a generic derogatory term, not necessarily relating to the marital status of one's parents.
"E-1 Vikings" - Echo Company, First Regiment, United States Corps of Cadets, United States Military Academy"F2 Zoo" – Foxtrot Company, Second Regiment, United States Military AcademyThe U.S. submarine USS Tunny (SSN-682)The weekly Alaskan newspaper the Nome NuggetWhitehorse Star, newspaper in the capital of the Yukon TerritoryUniversity of Idaho Navy ROTC Drill TeamThe comic strip Odd BodkinsU.S. Air Force 490th Missile Squadron "Farsiders", Malmstrom AFB, MTUS Army Special Forces 2nd Battalion, 1st Special Forces Group (Airborne), Joint Base Lewis-McChord, WashingtonInformal motto of The Fletcher School of Law and DiplomacyE-3 Dragons - Echo Company 3rd Regiment, United States Corps of Cadets, 1969-1973, United States Military AcademyThe Science Department of Chenango Forks High School in Binghamton, New York5 Troop, 66 Squadron, Junior Leaders Regiment, Royal Engineers (1988)Nil Carborundum, title of a 1962 play and TV comedy by Henry Livings.Referenced in the 1958 novel, Saturday Night and Sunday Morning by Alan Sillitoe.Nil illegitimum carborundum is referenced in the 1960 novel, A Kind of Loving by Stan Barstow.Nil bastardi carborundum" is referenced in The Life and Loves of a She-Devil by Fay WeldonNolite te bastardes carborundorum, in The Handmaid's Tale (1985) by Margaret Atwood.Illegitimi non carborundum, in Lucifer's Hammer (1977) by Larry Niven and Jerry PournelleIllegitimi non carborundum, in The Dark Design (1977) by Philip Jose FarmerNil illegitimo carborundum is a maxim credited to the fictional philosopher Didactylos in Terry Pratchett's Small Gods.Non Illegitimus Carborundum is the school motto of the fictional girls' school St. Trinian's, appearing on the school's coat of arms.Illegitimis non Carborundum is printed on a banner in the artwork for The Toasters' 7th studio album Don't Let the Bastards Grind You Down and Dee Snider's solo album Never Let the Bastards Wear You Down.Nil carborundum illegitimus is a phrase (sometimes abbreviated N.C.I) used by Kath Lewis in Donald Jack's novels Three Cheers for Me and That's Me in the Middle.Nil carborundum illegitimis is said by Landon Kettlewell in Cory Doctorow's MakersSpoken by "Ozzie", protagonist of the 1997 Patrick Stewart film Masterminds.Motörhead has a song called "(Don't Let 'Em) Grind Ya Down" on their Iron Fist album, in which the last phrase is "Don't let the bastards grind you down"."So don't let the bastards grind you down" is the chorus of the song "Acrobat", by U2.Inscribed on a watch given by the Member of Parliament Michael Mates to Asil Nadir of Polly Peck fame.Mentioned with translation by the Member of Parliament for Twickenham Toby Jessel in the House of Commons of the United Kingdom on June 7, 1993.Mentioned in the TV show The OC by Taylor Townsend at the end of her graduation speech.Mentioned by Premier of Newfoundland, Danny Williams in reference to a power deal with Nalcor Energy on February 20, 2009.Mentioned in the final episode "Richie" of the Australian TV series The Slap (2011)Stated by Janet King in the Australian Legal Drama Crownies (2011)The main character of the Alpha and Omega series by Patricia Briggs says the phrase.In the television series Third Watch, Doc's father has a wall plaque that bears the phrase, which is translated as "don't let the bastards get you down" by Doc.In the television series Porridge the character Norman Fletcher uses the phrase frequently to remind his fellow prison inmates to keep their spirits up.In the children's novel The Machine Gunners by Robert Westall, "Nil carborundum" is used twice.Van Morrison sings "won't let the bastards grind me down" in the song Raincheck