Sully

google

ref

late 16th century: perhaps from French souiller ‘to soil’.

wiktionary

ref

From Middle English sulen, sulien(“to become dirty; to defile, pollute, taint”), from Old English sylian(“to soil, pollute; to sully”), [1] from Proto-Germanic *suliwōną, *sulwōną, *sulwijaną(“to make dirty; to sully”), from Proto-Indo-European *sūl-(“thick liquid, muck”), perhaps conflated partially with Old French souillier(“to soil”) (modern French souiller) from the same Germanic source. The word is cognate with Danish søle(“to sully”), Dutch zaluwen(“to sully”) (Middle Dutch saluwen(“to sully”)), German sühlen(“to sully”), Old Saxon sulian(“to sully”), Swedish söla(“to sully”). Also compareMiddle English sulpen(“to defile, pollute”), [2]Old English solian(“to soil, become defiled, make or become foul”), and see more at soil.

etymonline

ref

sully (v.)

1590s, probably from French souiller "to soil," also figurative, from Old French soillier "make dirty" (see soil (v.)). Related: Sullied (1570s); sullying.