Is HALOS a Wordle Word?

Yes. HALOS 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 HALOS mean?

A circular band of coloured light, visible around the sun or moon etc., caused by reflection and refraction of light by ice crystals in the atmosphere.
A cloud of gas and other matter surrounding and captured by the gravitational field of a large diffuse astronomical object, such as a galaxy or cluster of galaxies.
Anything resembling this band, such as an effect caused by imperfect developing of photographs.

5 more noun definitions

Nimbus, a luminous disc, often of gold, around or over the heads of saints, etc., in religious paintings.
The metaphorical aura of glory, veneration or sentiment which surrounds an idealized entity.
(iconography) a circular annulus ring, frequently luminous, often golden, floating above the head
A circular brace used to keep the head and neck in position.
A rollbar placed in front of the driver, used to protect the cockpit of a open cockpit racecar.

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

Starter word rating: AverageIn the top 19% of all valid Wordle words for testing common letters.
Vowels: A, O
Unique letters: 5 of 5
Common letters: A, L, O

Hard-mode trap: 6 valid words fit the pattern HAL_S. 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.