The word "disparity" comes from the Latin disparitās, meaning "inquality", which is a combination of the prefix dis- ("not") and paritās ("equality").  The word passed through Middle French (disparité) before entering English.  The word's etymology emphasizes a lack of equality, similarity, or difference.  

According to the Oxford English Dictionary (OED), the earliest known use of the noun disparity in English was in the late 1500s.  The OED's earliest evidence is from before 1575, (possibly 1571), in the writings of Nicholas Harpsfield, religious controversialist and historian. 

Examples of "disparity" in a sentence: 
"In any case, the wide disparity of incomes and egos leads to a certain instability."  
"There was an enormous disparity in the lives of the rich and the poor in that country." 
"In Ohio, the racial disparities are even worse when compared to the rest of the country." 
"There was a huge free-throw disparity: the Lakers went to the line 37 times while the Warriors shot just 17 free throws." 

Just the facts:

DISPARITY Definition & Meaning - Merriam-Webster

DISPARITY Synonyms: 69 Similar and Opposite Words | Merriam-Webster Thesaurus

3 hours ago, drpaladin said:

Is it disparity that despairity isn't considered a real word?

Would your despairity have to do with a absolute loss of hope or breaking up couples, whether married or unmarried?  🤪