पूर्वसदृशसमोनार्थकलहनिपुणमिश्रश्लक्ष्णैः

A word ending in Instrumental -3rd case-affix is compounded with the words पूर्व 'prior', सदृश 'like', सम 'similar', ऊनर्थ 'words having the sense of less', कलह 'quarrel', निपुण 'proficient', मिश्र 'mixed' and श्लक्ष्ण 'polished sleek', and the resulting compound is तत्-पुरुष ।
From this sutra, we learn incidentally that the words पूर्व, &c., govern the instrumental case.

As, मासेन पूर्वः = मासपूर्वः 'prior by a month,' संवत्सरपूर्वः 'prior by a year,' मातृसदृशः 'like the mother,' पितृसदृशः 'like the father,' मातृसमः 'similar to the mother,' पितृसमः 'similar to the father,' माषोनम्, माषविकलं 'less by a masha, असिकलहः'a fight with the swords,' वाक्कलहः 'bandying words.'वाग् निपुणः 'proficient in speech,' आचारनिपुणः 'proficient in the observances of sacred duties,' तिलमिश्रः — गुडमिश्रः 'mixed with sesamum or jaggery' आचारश्लक्ष्णः 'polished in behaviour.'

Vart :-The word अवर should be enumerated in the list, as मासावरः 'later than a month.'