The word "discretion" came to Middle English (in the sense ‘discernment’): via Old French from the Latin discretionem, meaning "discernment" or "separation," and is derived from the verb discernere, which means "to separate" or "to distinguish". The term entered English around the 13th or 14th century, initially referring to the ability to perceive and understand, and later evolving to encompass moral judgment, prudence, and the power to make one's own decisions. 

According to the Oxford English Dictionary, the earliest known use of the word discretion in English dates to the Middle English period (1150-1500), with evidence from before 1325 in the Statutes of the Realm. 

Examples of "discretion" used in a sentence: 
"Each artist in the gallery has discretion over the price that will be charged for his or her work." 
"The coach used his own discretion to let the injured quarterback play."
"He always uses care and discretion when dealing with others."
"She handled the awkward situation with great discretion." 
"Larsson sometimes joined in the fun, but with more discretion." 
"This committee may want to exercise its discretion to look into those charges." 
"Courts would have the discretion to impose a community order." 
"He appreciated his discretion and his fidelity." 

Just the facts:

DISCRETION Definition & Meaning - Merriam-Webster

Websters 1828 - Webster's Dictionary 1828 - Discretion

DISCRETION Synonyms: 138 Similar and Opposite Words | Merriam-Webster Thesaurus