Tattoo is a loanword from the Samoan word "tatau", meaning "to strike". The "Oxford English Dictionary" gives the etymology of tattoo as "In 18th c. tattaow, tattow. From Polynesian (Samoan, Tahitian, Tongan, etc.) tatau. In Marquesan, tatu." Before the importation of the Polynesian word, the practice of tattooing had been described in the West as painting, scarring or staining. The etymology of the body modification term is not to be confused with the origins of the word for the military drumbeat or performance — see "military tattoo". In this case, the English word "tattoo" is derived from the Dutch word "taptoe".
Longest word in English major English language dictionaries is "pneumonoultramicroscopicsilicovolcanoconiosis", a word that refers to a lung disease contracted from the inhalation of very fine silica particles, specifically from a volcano; medically, it is the same as silicosis. The word was deliberately coined to be the longest word in English, and has since been used in a close approximation of its originally intended meaning, lending at least some degree of validity to its claim. The "Oxford English Dictionary" contains "pseudopseudohypoparathyroidism" (30 letters). "Merriam-Webster's Collegiate Dictionary" does not contain "antidisestablishmentarianism" (28 letters), as the editors found no widespread, sustained usage of the word in its