3rd person plural optative (conditional) of sampāpuṇati; the form sampāpuṇeyyuṁ is an alternative construction with -eyyu + plural -ṁ
Analysis. sam- (together, completely) + pā- (forward, forth) + √puṇ (to fill, reach, arrive); the prefix pair sam- + pā- intensifies the sense of complete attainment.
Etymology. √puṇ is related to Latin plēnus 'full' and English full (both from PIE *peleH₂-). The prefixes sam- and pā- build a sense of bringing something to completion: literally 'fill together' → 'reach, attain completely'.
Meanings from the Digital Pāḷi Dictionary; morphology and etymology by Claude.
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