-o
suffix used for making colloquial or slang nouns and nicknames. In Australia, where there was no influence from Spanish, this suffix originated from early nominal uses of the cries of various street vendors. Thus the milkman used to sing out 'milk-oh!' and so became the
MILKO, the rabbit seller cried 'rabbit-oh!' and so became the
RABBIT-O. It is appended to monosyllablic words or to the first syllable of polysyllabic words
AUSTRALIA, 1865