sandhi form: ca + atthāya
Analysis. ca (and) + atthāya (for the sake of, instrumental/allative of attha). The conjunction ca joins this purposive phrase to a preceding clause or noun.
Etymology. attha descends from Sanskrit artha (purpose, object, meaning); cognate with English art (skill directed at an object) and Greek arthron (joint, articulation—that which fits together purposefully). The suffix -āya forms an allative/dative expressing purpose or destination. ca is the coordinating conjunction and, cognate with Latin que and Sanskrit ca.
Meanings from the Digital Pāḷi Dictionary; morphology and etymology by Claude.
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