Oxford Dictionaries online lists pneumonoultramicroscopicsilicovolcanoconiosis as a noun. The definition is "an artificial long word said to mean a lung disease caused by inhaling very fine ash and sand dust."
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pneumonoultramicroscopicsilicovolcano is longer . it has 37 letters .as hippopotomonstrosesquippedaliophobia had 36
Maybe 19
The part of speech for this particular word is a noun.
part of speech
The part of speech for "answer" is a noun.
adverb
what part of speech is beneath
The part of speech for "unfamiliar" is an adjective.
The part of speech of "came" is a verb.
The part of speech for "twirl" is a verb.
The part of speech for "explicit" is an adjective.
The part of speech for "indefinite" is an adjective.