Excelsior, a Latin comparative word often translated as "ever upwards" or "even higher", has a long literary history, whether that's the 1841 poem by Henry Wadsworth Longfellow, a 1948 short story by P. G. Wodehouse, the poem by Walt Whitman, an 1879-1931 brass band from New Orleans, the motto of the fictional Weldon Institute in Jules Verne's Robur the Conqueror, an 1881 ballet by Luigi Manzotti and is the official motto of the state of New York.
It was also used by the late Stan Lee as a sign-of for his Stan's Soapbox editorial column in Marvel Comics and became quite his catchphrase. In the Marvel Universe, it was also used in the Marvel comic book Runaways as the name of a support group for former teenage superheroes. But maybe not any more.
Bleeding Cool has learned that Marvel is choosing not to use the word "Excelsior" in their comic book publications any more. It recently had a revival when Marvel started reprinting his Stan's Soapbox columns, but it was pointed out that the word has just been trademarked by his old company POW Entertainment, as of August this year. And as a result, Marvel has stopped using the word in editorial or referenced by comic book characters in the comics. It doesn't come up a lot, but with Marvel publishing a number of books set in earlier continuity and reprising and recreating classic comic books, it has a greater chance than before to pop up.
Legally, there is nothing to stop Marvel using the phrase, unless POW Entertainment could make the case that Marvel was trading on its name. But for now, let's let Stan Lee have the last word. You, of course, know exactly what that word is.