'indecent exposure' is a compound of 'indecent' and 'exposure'. 'indecent' originates from Latin via Old French, from Latin 'indecent-' (from 'in-' 'not' + 'decens'/'decere' meaning 'befitting, proper'); 'exposure' originates from Latin 'exponere' ('ex-' 'out' + 'ponere' 'to put'), via Old French and Middle English.

'indecent' passed into English via Old French (e.g. 'indecent') and Middle English with the sense 'not fitting or proper'. 'exposure' comes from Latin 'exponere' to Old French 'exposicion' and Middle English 'exposicion'/'exposure', and the two elements were combined in modern English to describe the act of unveiling or showing something inappropriate publicly.

Originally, 'indecent' meant 'not fitting or proper' and 'exposure' meant 'the act of putting out or exposing'; combined, the phrase came to mean specifically 'the act of displaying parts of the body considered private or improper in public,' and in modern usage it commonly denotes a criminal offense involving the deliberate public display of genitals or other private parts.