Is SKELL a Wordle Word?

Yes. SKELL is a valid Wordle word.

It is not on the Wordle answer list, so it is unlikely to be a daily answer.

What does SKELL mean?

A homeless person, especially one who sleeps in the New York subway.“Did you see those two skells lying in the doorway?”
(police jargon) A male suspicious person or crime suspect, especially a street person such as a drug dealer, pimp or panhandler.

Definition from Wiktionary, available under the CC BY-SA license.

Starter word rating: WeakIn the top 66% of all valid Wordle words for testing common letters.
Vowels: E
Unique letters: 4 of 5Repeats L
Common letters: E, L

Hard-mode trap: 7 valid words fit the pattern S_ELL. If you reach it, you may need several guesses to find the last letter.

Letter ratings use how often each letter appears in Wordle answers.

Tap its tiles to the colours Wordle showed, and the Wordle Solver lists every word that still fits, with the best next guess.