From Old Frenchregret(“lamentation, complaint”), deverbal of regreter(“to lament”), from re-(intensive prefix) + *greter, *grater(“to weep”), from Frankish*grētan(“to weep, mourn, lament”), *grēotan(“to cry, weep”), from Proto-Germanic*grētaną(“to weep”), *greutaną(“to weep, cry”), from Proto-Indo-European*ghrew-(“to weep, be sad”).