ऊनार्थकलहं तृतीयायाः

The acute accent (उदात्त) falls on the final of words having the sense of ऊन and of कलह when they are second members in a compound, preceded by a term in the Instrumental -3rd case.
Thus माषोन꣡म्, कार्षापणोन꣡म्, मासविकल꣡म्, कार्षापणविकल꣡म्, असिकलहः꣡, वाक्कलहः꣡ ॥ The compounding takes place by 2.1.31. This is an exception to 6.2.2 by which the first member being in the third case, would have retained its original accent, Some say that the word अर्थ in the sutra means the word-form अर्थ, so that the aphorism would mean - "after an Instrumental case, the words ऊन, अर्थ, and कलह get acute on the final". The examples will be in addition to the above:- धान्येनार्थाः = धान्यार्थः꣡ ॥ If this be so, then the word-form ऊन alone will be taken and not its synonyms like विकल &c. To this we reply, that ऊन will denote its synonyms also, by the fact of its being followed by the word अर्थ ॥ By sutra 2.1.31, ऊनार्थ and कलह 2.1.57 always take the Instrumental case, so we could have omitted the word तृतीयायाः, from this sutra, for by the maxim of pratipadokta &c, ऊनार्थकलहं would have referred to the compound ordained by 2.1.31. The mention of तृतीया here is only for the sake of clearness.