Is MULES a Wordle Word?

Yes. MULES is a valid Wordle word.

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

Plurals ending in S are almost never chosen as Wordle answers.

What does MULES mean?

/mjuːlz/

The generally sterile male or female hybrid offspring of a male donkey and a female horse.
The generally sterile hybrid offspring of any two species of animals.
A hybrid plant.

7 more noun definitions

A stubborn person.
A person paid to smuggle drugs.
A coin or medal minted with obverse and reverse designs not normally seen on the same piece, either intentionally or in error.
A MMORPG character, or NPC companion in a tabletop RPG, used mainly to store extra inventory for the owner's primary character.
Any of a group of cocktails involving ginger ale or ginger beer, citrus juice, and various liquors.
A kind of triangular sail for a yacht.
A kind of cotton-spinning machine.

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

Starter word rating: AverageIn the top 28% of all valid Wordle words for testing common letters.
Vowels: U, E
Unique letters: 5 of 5
Common letters: L, E

Hard-mode trap: 8 valid words fit the pattern _ULES. 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.