क्षेत्रियच् परक्षेत्रे चिकित्स्यः

The word क्षेत्रियच् (क्षेत्रिय) is anomalous meaning 'curable in another body' i.e. 'not curable in this life'.
The whole word enunciated here in the sense of para-kshetre chikitsya; or the word क्षेत्रिय, with acute on the last syllable, is formed by adding the affix घच् to the word परक्षेत्र, the force of the affix being 'curable therein' and the word पर is elided before this affix. Thus क्षेत्रियो व्याधिः 'incurable disease'. क्षेत्रियं कुष्ठं 'incurable Ieprosy': i.e. --organic disease. The word परक्षेत्र means body assumed in the next reincarnation. The word क्षेत्रिय applies to an irremediable disease.

The word क्षेत्रियं means 'poison' also = यत् परछेत्रे परशरीरेसंक्रमय्य चिकित्स्यते ॥ 'that which is to be removed from another's body where it has entered'. Or क्षेत्रिय means 'rank growth or grass', i.e. यानि सस्यार्थे क्षेत्रे जातानि चिकित्स्यानि नाशयितव्यानि ॥ "that like grass &c, which grows in a para-kshetra or another's field i. e. a field set apart for grain &c, and not for grass, and which therefore must be weeded out (chikitsya)" Or क्षेत्रिय is an 'adulterer', i.e. परदाराः परक्षेत्रं, तत्र चिकित्स्यः निगृहीतव्यः ॥ These are all secondary meanings.