"Explore" originates from the Latin explorare, meaning "to investigate, search out, or examine", which likely began as a 16th-century hunting term for scouting game by shouting.  It combines ex- ("out") and plorare ("to cry out or weep"), indicating a literal, early sense of "crying out" to reveal something.  Explore entered English in the late 1500s from Middle French explorer.  The term evolved from its literal "crying out" meaning to broader, more general investigations by the 1580s.  The definition expanded even further in the 1610s to include traveling to a new country for the purpose of making discoveries.  Explore entered English in the late 1500s from Middle French explorer.  Explore shares the plorare (cry) root with "deplore" (to cry out against) and "implore" (to call out to/beseech). 

According to the Oxford English Dictionary, the verb explore was first used in English in the mid-1500s.  The earliest evidence cited by the OED is from 1531, appearing in a translation by the Scottish poet and translator John Bellenden.  The noun explore appeared much later, with the earliest evidence in the 1870s (1873), utilized by physician Thomas Watson.  The noun exploration is recorded slightly later, in the mid-1500s (1544) in Acts of Parliament.  The noun explorer is attested from the 1570s, while the noun explorement appeared in the mid-1600s.  

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EXPLORE Definition & Meaning - Merriam-Webster

EXPLORE Synonyms: 36 Similar Words | Merriam-Webster Thesaurus

EXPLORATION Definition & Meaning - Merriam-Webster