Tulu language has lot of words that end with -o sound. For example ‘kuLo’ which means lake (or a water body). The ‘o’ suffix corresponds to -aṁ and -a in Tamil/Malayalam and in Kannada respectively, i.e., lake is kuLaṁ in Tamil & Malayalam and koLa in Kannada.
The usage of -o suffix can be noticed more commonly in southern dialects of Tulu. In northern dialects, especially around Udupi and Karkala the -o suffix replaced by -a.
The researchers had concluded that the -o suffix got attached with Tulu words by the influence of Prakrit language. Tulu underwent to influence of Prakrit language during the era of emperor Ashoka, i.e., Prakrit used to be an administrative language of larger parts India.
Hindi and Bengali languages were derived from Prakrit language, which have words ending with -o suffix.
Hindi words ending with -o suffix.
āvo= come
Nācho= dance
Gāvo= sing
Bengali words ending with -o suffix.
Pūjo (pūja) =worship
Borṇo (varṇa) =color
Reference
TuLu Research & Studies – 422