sup (v.1) Look up sup at Dictionary.com
"eat the evening meal," c.1300, from Old French super, soper "dine, sup, dip bread in soup or wine, sop up" (Modern French souper), which probably is from soupe "broth" (see soup), until recently still the traditional evening meal of French workers.
sup (v.2) Look up sup at Dictionary.com
"to sip, to take into the mouth with the lips," Old English supan (West Saxon), suppan, supian (Northumbrian) "to sip, taste, drink, swallow" (strong verb, past tense seap, past participle sopen), from Proto-Germanic *supanan (cognates: Old Norse supa "to sip, drink," Middle Low German supen, Dutch zuipen "to drink, tipple," Old High German sufan, German saufen "to drink, booze"), from PIE *sub-, possibly an extended form of root *seue- (2) "to take liquid" (cognates: Sanskrit sunoti "presses out juice," soma; Avestan haoma, Persian hom "juice;" Greek huetos "rain," huein "to rain;" Latin sugere "to suck," succus "juice, sap;" Lithuanian sula "flowing sap;" Old Church Slavonic soku "sap," susati "suck;" Middle Irish suth "sap;" Old English seaw "sap").