The word concinnity comes from the Latin concinnitas, meaning "skillfully put together".   It is derived from the Latin adjective concinnus and the verb concinnare, which both relate to making something neat and orderly. 

According to the Oxford English Dictionary, the first known use of "concinnity" in English was in 1531. in the writings of humanist and diplomat Thomas Elyot, in particular in his treatise, "The Boke Named The Governor.  

Examples of "concinnity" used in a sentence: 
"The chorus's seamless concinnity of voice and instrument was praised by critics for its perfect harmony and elegance." 
"The novel's concinnity, achieved through the skillful weaving of its plot threads, made it a pleasure to read," 
"Critics praised the film's visual concinnity, noting how well the lighting and set design worked together."  
"The architect's design was celebrated for its concinnity, with each part fitting together harmoniously to form a beautiful whole."  
"Her writing is known for its concinnity, combining clarity with a skillful elegance of style." 
"Novak was delighted by his concinnity, and even more delighted by the treatments on offer that day at the storefront franchise spa concept."  

Just the facts:

CONCINNITY Definition & Meaning - Merriam-Webster

CONCINNITY Synonyms: 37 Similar and Opposite Words | Merriam-Webster Thesaurus