espionage

Recorded in English since 1793, espionage comes from French espionnage, from espionner ("to spy"), ultimately from Old French espion ("spy"), which traces back through Frankish *spehōn to Proto-Germanic *spehōną ("to spy, peek, peer").

The initial s of espion had actually fallen silent in French since the 13th century, but it was restored in modern pronunciation under the influence of Italian spione ("spy") — and English speakers adopted that restored s-sound too.

It shares its Proto-Germanic root, *spehōną, with the English word spy.