Etymology: There are four parts of speech or சொல் in Tamil, namely பெயர் (noun), வினை (verb), இடை (particles) and உரி (attributives). It is an accepted principle with Tamil grammarians that all parts of speech are ultimately reducible to only two— substantives and verbs : and this is also the view of modern philologists. Says Tolkapyar,
சொல்லெனப் படுப் பெயரே வினையென்
றாவிரண் டென்ப வறிந்திசி னோரே.-II, 160.
Of these the noun and the verb require no explanation. இடைச்சொல் means the middle word—that is a part of speech common to both nouns and verbs. It consists of all particles, terininations or postpositions which go to change or modify the meaning of nouns and verbs with reference to time, place, subject, action, &c. Thus it embraces the particles of tense, personal terminations, case endings, demon. strative letters, conjunctions, interjections, euphonic expletive particles, and in fact every particle that has no meaning by itself, independent of the noun or verb to which it is attached. உரிச்சொல் treats of the various qualities of nouns and verbs, and it therefore includes adjectives and adverbs. The metaphysical explanation of உரிச்சொல் given by Sivagnanamuni is, —குணப்பண்பும் தொழிற்பண்புமாகிய பொருட்பண்பையுணர்த் துஞ்சொல் உரிச்சொல். Elsewhere, he goes on to say that நட, வா, முதலிய முதநிலைகளும் தொழிற்பண்பை யுணர்த்தஞ் சொற்களாகலின் உரிச்சொல் லேயாம். This explanation seems to me very obscure, and it is the
