The answer is yes, "unusual spelling" is a correct and usable phrase in written English.
You can use it when you want to refer to spelling that does not conform to standard orthography. For example: "The author used some unusual spelling to set his work apart from other authors."
It has an unusual spelling, but it is one in keeping with the era.
She adopted the unusual spelling of her nickname, Susie, after seeing the Picasso collage "Glass and Bottle of Suze".
He divided it into 25 chapters (against Brod's 20) and revealed innumerable peculiarities, like Kafka's sparse punctuation and unusual spelling.
"Our name has always been important to me because of its unusual spelling," said Ms. Grace, 61.
One watermark said "VenterInstitvte," using the unusual spelling because there is no amino acid represented by the letter "u".
The unusual spelling of her first name, combined with the cool, Irish-tough profunciation of her last — "Mackie" — made her what today might be called a brand, though the concept would have repelled her.
But the filmmakers' deft interweaving of old videos with recent interviews casts an unusual spell, inducing a poignant kind of magical thinking.
DESPITE unusual spells of mild weather, part of it called the January thaw, this has been a rough winter for plants.
In late November, as the Yucatán experienced an unusual spell of cool weather, I boarded a second-class bus in downtown Cancún to begin a trip inland and underground, a half-dozen cenotes on my itinerary.
Of the 387,000 jobs created last month, nearly half -- 169,000 -- were a result of an unusual spell of warm weather in mid-January, just when her department was taking its monthly job survey, she said.
There is a lot of interest in the history of climate because one way of thinking about the last 10,000 years — geologists call it the Holocene — is that we've been lucky to have an unusual spell of really nice weather in which civilization as we know it could develop.
