nominative plural + iti (quotation marker)
Analysis. sikkhāpade (nominative plural of sikkhāpada) + sūti (contraction of su + iti, 'thus' / 'so-called'); the phrase marks training rules as a class: 'the precepts, so to speak' or 'the so-called precepts'.
Etymology. sikkhāpada is sikkhā (training, learning; from √śikṣ, 'learn, be trained'; no common European cognate, but Sanskrit śikṣati 'learns') + pada (foot, step, topic, ground; from √pad 'go, fall'; cognate with English foot, Latin pes, Greek pous). Literally 'training-step' or 'step of training', the metaphor is of walking the path of discipline — each precept a footstep.
Meanings from the Digital Pāḷi Dictionary; morphology and etymology by Claude.
Lite mode — plain HTML for e-readers and old browsers. Full version