From Wiktionary, the free dictionary
Perhaps from the endings of Italian maestro, German Meister and Bürgermeister, and French bourgmestre.[1]
-estro
- shows the chief or boss of something
- ŝipo (“ship”) + -estro → ŝipestro (“captain”)
- ^ André Cherpillod, Konciza Etimologia Vortaro, 2007