"Discovery" originates from the 14th-century Middle English discoveren, derived from Old French descoverir (uncover, reveal) and Late Latin discooperire, meaning "to uncover" or "unroof".  It combines the prefix dis- (opposite of/removal/navigation) with cooperire (to cover).  Originally meant to divulge, betray, or "lay open to view", a usage now considered obsolete, which referred to revealing or exposing secrets.  The shift from exposing secrets to the literal "obtaining sight or knowledge of something previously unknown" occurred around the mid-16th century.   The noun discovery was formed on the pattern of recover/recovery. 

According to the Oxford English Dictionary (OED), the earliest known use of the noun discovery is in the early 1500s, with the earliest evidence appearing before 1527 in the writings of Robert Thorne.   The verb discover appeared much earlier, in Middle English in the 1330s. The noun discovering was used in the mid-14th century, prior to the noun discovery.  

The doctrine of discovery was rooted in papal bulls issued in the 1400s (e.g., 1493), which provided religious and legal justification for Christian empires to claim non-Christian lands.   The term "discovery" was used to describe the first arrival of Europeans in new territories, legitimizing the seizure of land from indigenous peoples.   It was formally applied in U.S. law by Supreme Court Justice John Marshall in the 1823 case Johnson v. M'Intosh, which established that European "discovery" gave title to the land, invalidating Indigenous rights.  The term is now heavily criticized and has been formally repudiated by institutions like the Vatican, as it facilitated colonialism. 

Just the facts:

DISCOVERY Definition & Meaning - Merriam-Webster

DISCOVERY Synonyms: 25 Similar and Opposite Words | Merriam-Webster Thesaurus

DISCOVER Definition & Meaning - Merriam-Webster

SELF-DISCOVERY Definition & Meaning - Merriam-Webster