accusative singular neuter of paccuppannasukha, a compound adjective/noun
Analysis. pacc-uppanna-sukhaṁ: paṭi (back, against) + uppanna (arisen, present) + sukha (happiness); 'happiness that stands forth right here' — the pleasure of the immediate moment, contrasted with sukha of future rebirth or nibbāna.
Etymology. paṭi- 'back, against, counter' (Greek proti) + uppanna 'arisen' (ud 'up' + √pad 'arise') + sukha 'ease' (su 'well' + kha, probably *sthā 'stand'); the compound emphasizes what is present and pressing in this very moment.
Meanings from the Digital Pāḷi Dictionary; morphology and etymology by Claude.
Lite mode — plain HTML for e-readers and old browsers. Full version