A Comparative Grammar of the Modern Aryan Languages of India v2.c12.36

v2.c12.36

§ 3. Stems in -a. The nouns of this class are of all three genders, and make in the nominative case of Skr., masc. -as, fem. -â, neut. -am. The s of the masc. nom., however, is not permanent; before a word beginning with a sonant letter, it, together with the a of the stem, changes into o. Inasmuch as the sonant letters in Sanskrit are more numerous than the surds, the form of the nominative case in -o was much more frequently heard than any other; and the vulgar, who are not careful of minute grammatical distinctions, appear even in the earliest times to have used the termination in -o to the exclusion of all others. Thus Vararuchi (v. 1) gives it as a general rule that o is substituted for su (= as), the technical name of the nom. sing. ending, in all words whose base ends in a, as vachchho, vasaho, puriso, for vrikshas, vrishabhas, purushas. He considers that the a of the suffix has been elided, though it is more probable that the whole termination -as changed into -o through the intermediate form -ah, the labial vowel owing its origin to the involuntary contraction of the