Latin excelsior "higher," comparative of excelsus (adj.) "high, elevated, lofty," past participle of excellere "to rise, surpass, be superior, be eminent," from ex "out from" (see ex-) + -cellere "rise high, tower," related to celsus "high, lofty, great," from PIE root *kel- (2) "to be prominent; hill." Taken 1778 as motto of New York State, where it apparently was mistaken for an adverb. Popularized 1841 as title of a poem by Longfellow. As a trade name for "thin shavings of soft wood used for stuffing cushions, etc.," first recorded 1868, American English.
