"A historic" or "an historic"?
A well known grammar rule says that we should use an before vowel sounds; for example, an accident, an item, an hour. We use a otherwise: a book, a hotel, a university.
SummaryA historic is more common in online writing, but both usages are sufficiently common to be considered correct.
Notice that we say an hour, not a hour. The choice of a or an is based upon the sound of the word, not the spelling. Hour sounds as if it starts with a vowel sound (ow); hence, we use an.
Following this rule, we would say a historic, not an historic because (for most speakers) historic doesn't start with a vowel sound.
Words of three or more syllables that start with h are treated differently by some speakers, though. (This may be because of the tendency of some regional accents to drop initial Hs.)
Here's another example. Which of these pairs of sentences sounds better to you?
- We can't agree on a hypothesis.
- We can't agree on an hypothesis.
There is a clear preference on the web in favour of a hypothesis and a historic. Even so, a significant minority uses the other form. This supports the view that both forms are widespread. Which form you use seems to be little more than a personal preference and perhaps a matter of accent.
In summary: A historic is more common in online writing, but both usages are sufficiently common to be considered correct.