According to Indian system of attaining knowledge, all knowable knowledge was divided by the thinkers into six main categories viz., tarka (Logic), vyaakaraNa (grammar), dharma (law), miimaaMsa (theology), vaidya (medicine) and jyoetishya (astrology). Correspondingly, six main categories of sciences were developed with suitable texts for the use of the learners in the respective fields. These are called ‘shaT Saastraas’ (meaning – Six sciences) and one of them the ‘vyaakaraNa Saastra’ (Science pertaining to the grammar of words) had been dealt with extensively by the scholars of the Sanskrit language, encompassing all the aspects of that language. Simultaneously, for the help of the seekers of Vedic knowledge, subsidiaries to veadaa, known as veadaaMga were developed.
These subsidiary texts also featured ‘vyaakaraNa Saastra’ as one of them and the remaining five dealt with pronunciation and articulation of words (known as Siksha), performing of religious ceremonies (kalpamu), astrology (jyoetishyamu), prosody (ChaMdamu) and the last one, knowledge regarding the meaning of difficult and obscure words and phrases that occur in the veadaa (known as niruktamu). It is widely believed that yaaskaachaarya’s ‘niruktamu’ is the first ever lexicon for Vedic literature, in which the aachaarya had explained the origins of certain difficult words that were used in the four veadaa, duly mentioning the corresponding ‘base words’ called ‘dhaatu Sabda’ for each word and collected them into a compendium of difficult words and named it as ‘niruktamu’.