Note: Parallel formations are Old Frisian plichta "to be liable (for)," Middle Dutch plichten, plechten "to pledge, commit," Middle High German phlichten "to take part, oblige, pledge," perhaps pointing to descent from a verb already formed in West Germanic.

Note: As has long been acknowledged, the ulterior origin of *plehan-/*plegan- is problematic. The original meaning of the verb is not entirely clear, and the initial p- presupposes *b-, which existed marginally, if at all, in the Indo-European parent language of Germanic. E. Seebold (Vergleichendes und etymologisches Wörterbuch der germanischen starken Verben, The Hague, 1970) takes as the primary meaning "to stake (as an amount in a game)," from which both "expose to danger" (as in Old English) and "to act as guarantor for, look after, direct, be accustomed to" (as elsewhere in Germanic) proceed. Seebold further attaches to this verb Old English plegan, plegian "to move quickly, occupy oneself, dance, play" (see play entry 1). R. Lühr, et al. (Etymologisches Wörterbuch des Althochdeutschen, Band 6), however, take the original meaning of the Germanic verb to have been "to make, do," from which all the other senses proceed (they point to the many nuances of Latin facere "to do, make"). As an etymological explanation, they compare Middle High German spulgen "to maintain, be accustomed, use" (< Germanic *spulǥ-ii̯e/a-) and suggest that *plehan-/*plegan- was formed from the same base by loss of a presumed mobile s after the Germanic sound shift (hence preserving p). They see the verb as ultimately formed by root extension from Indo-European *(s)pelH- "split off, separate" and connect it with the etymon of plow entry 1.

Note: The forms with -i- and final t (or -te), which predominate in both Anglo-French and Middle English, appear to merge the i of pli (compare Old French plei, ploi, Middle and Modern French pli, and see ply entry 2) with the final consonant of plait, pleit, ploit. The Anglo-Norman Dictionary uses pli as the headword, but the citations given show no examples. Middle English forms such as pliȝt, plyght show assimilation to plight entry 2, of which the Middle English senses "danger, harm, etc.," are not far distant; the Middle English Dictionary enters both words under a single entry plight.