'luminary' originates from Latin, specifically the word 'lūminārius', where 'lūmen' meant 'light' and the suffix '-ārius' denoted 'connected with' or 'pertaining to'.

'lūminārius' passed into Late Latin and then into Middle English (via Old French or directly through Medieval Latin) as forms such as 'luminarie' before becoming the modern English 'luminary'.

Initially, it referred to something relating to or providing light ('pertaining to light'); over time it also came to mean a person who 'sheds light' figuratively—that is, an eminent or inspiring person.