aon(in comp. aon-, aoin-), one, a single one, only, the only (often with amháin); the one, the same, any; at all, with neg. no, none, not any: aon is fiche, aon ar fhichid, twenty-one; aon duine, aon neach, any one, anybody; with neg., no one, nobody; aon eile, another; aon lá amháin, one day, once upon a time; aon le, together with; aon nídh, anything; with neg., nothing; aon uair, aon uair amháin, once, once upon a time; ar aon, together; mar aon, along with, together with; gach aon, every one. aon is sometimes accented, and forms one word with the following nouns, as: bhíomar araon ar aon-scoil, we both attended the same school; comhrac aon-fhir, single combat; but it is not accented in phrases like ní haon mhaitheas duitbheith ag cainnt, there is no use in your talk; níl agam acht aon scilling amháin, I have but a single shilling, and should then be regarded as a separate word. The accentuation of aon takes place when emphasis is to be laid on the singleness, unity, or identity of the idea conveyed by the following word; thus, níl aon bhrígh leis an bhfocal sain, that word has no meaning; but aoin-bhrígh is eadh atá leis an dá fhocal, both words have one and the same meaning. In the first of these two sentences aon is not emphasised, and should not form one word with brígh. If the word amháin follow in the sentence it sometimes takes the emphasis off aon. aon was in the 16th century, and is in modern times, often written éan, and in compounds aoin becomes éin. an objection to these forms is this, that frequently in poetry aon has to be pronounced aoin (with broad n), which is a recognised sound of ao in Con. and U.; but the spelling éan does not lend itself to that sound.