Disdain came to English as desdeyn (mid 14th century) "scorn, a feeling of contempt mingled with aversion," earlier dedeyne (c. 1300), from Old French desdeigne (Modern French dédain [noun]), from desdeignier [verb], based on Latin dedignari, from de- (expressing reversal) + dignari ‘consider worthy’ (from dignus ‘worthy’).   

According to the Oxford English Dictionary, the verb "disdain" first appeared in English in the mid 14th century (around  the 1300s). Specifically, the OED notes the earliest instance as "disdeinen" (or "desdainen") in Middle English, meaning "to think unworthy or worthless, to look upon with contempt". 

Examples of disdain used in a sentence: 
"His eyes blaze with contempt and disdain for you and your people." 
"She disdained his offer of help." 
"He disdains experts and gets his information from popular media." 
"She is a disruptive artist who disdains convention." 
"I disdain white tablecloths," said the waiter serving red wine disdainfully." 
"One of the first things they learned was to disdain the outward show of religion." 
"It is not surprising that they showed such disdain." 
"She looked me up and down and had complete disdain on her face from the way I looked." 
"He emerged from the pack as he has done so often before, mowing them down in the second half of the race with complete disdain." 
"He suffers no fools gladly, but pursues interesting people at any hour of day or night, for he has utter disdain for social convention." 
"My wife gave me a look of utter disdain and left the room." 

Just the facts:

DISDAIN Definition & Meaning - Merriam-Webster

DISDAIN Synonyms: 140 Similar and Opposite Words | Merriam-Webster Thesaurus