This term is precisely an adjective, but is generally known as the long article. Its used before nouns regarding the single quantity just, and signifies one, or any, but significantly less emphatically. Such expressions as “twice an hour,” “once an age,” a shilling an ounce (see 2d a, 2), this has a distributive force, and it is equal to each, every.
Coordinate usage: And; same as and, A.
Conditional usage: If; just like and, B.
an early on type of upon, retained before the final century in some phrases, as a benefit, a conclusion, now just on advantage, at a stretch; in present use only as an unfelt prefix an- or paid down a-. See an-, a-.
A prefix of Anglo-Saxon origin, just like on- and a-, occurring unfelt in anent, anon, anan, aneal, aneal, etc., with accent in anvil (however in this many other words perhaps originally and-: see an).
A prefix of Anglo-Saxon origin, a diminished kind of and- (which see), occurring unfelt in response.
A prefix of Latin origin, often an assimilation of ad- before n-, such as annex, annul, announce, etc., but occasionally representing Latin in-, such as anoint, annoy.
A prefix of Latin source, a low form of ambi-, happening (unfelt in English) in ancile, ancipital, anfractuous, etc.
A prefix of Greek beginning, the fuller kind of ἀ- privative (a-) maintained before a vowel, such as anarchy, anarthrous, anecdote, anomaly, etc.
A prefix of Greek source, the type of ana- before a vowel, as with anode.
A suffix of Latin source, forming adjectives that are or might also used as nouns.