Is it "a" or "an" in front of Greek letters beginning with a vowel?

Question

Good evening!

I know that it is a basic rule in English that before most vowels, the indefinite particle a becomes an. My question now is: Does this also apply in front of (non-latenized) Greek letters?

For example, is it "a $\omega$-invariant" or "an $\omega$-invariant"?

It's the sound, not the letter. Thus, you carry an umbrella but you wear a uniform. — John Douma, Aug 18 '22 at 22:45
Thank you! I was like 99% sure this was the case, but better safe than sorry ^^ — Symplectic Witch, Aug 18 '22 at 22:52
You can check these by using Google, add quotes around and search for it, like a ω-invariant. You get lots of things like $A(\omega)$, and you find many more results for the "an" version. — Suzu Hirose, Aug 18 '22 at 23:16

score 4 · Accepted Answer · answered Aug 18 '22 at 22:52

The rule is whether the pronunciation of the letter name starts with a vowel. So:

Use an before $\alpha$, $\epsilon$, $\eta$*, $\iota$**, $\omicron$, $\upsilon$, and $\omega$.
Use $a$ before all other Greek letters.

(* Unless you pronounce it "heta".)

(** Unless you pronounce it "yota".)

Is it "a" or "an" in front of Greek letters beginning with a vowel?

1 Answers1