Is MILER a Wordle Word?

Yes. MILER is a valid Wordle word.

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

What does MILER mean?

/ˈmaɪləɹ/

(often in combination) An athlete or a horse who specializes in running races of one mile, or a specified number of miles.
(in combination) A race whose length is the specified number of miles.“I ran an eight-miler on Sunday and I'm still feeling sore.”

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

Starter word rating: GoodIn the top 8% of all valid Wordle words for testing common letters.
Vowels: I, E
Unique letters: 5 of 5
Common letters: I, L, E, R

Hard-mode trap: 7 valid words fit the pattern _ILER. 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.