plaint (n.)youdaoicibaDictYouDict[plaint 词源字典]
"expression of sorrow," c. 1200, from Old French plainte "lament, lamentation" (12c.), from Latin planctus "lamentation, wailing, beating of the breast," from past participle stem of plangere "to lament, to strike" (see plague (n.)). Connecting notion probably is beating one's breast in grief.[plaint etymology, plaint origin, 英语词源]