The story
- Japanese · borrowed from択捉
- Ainu · derived fromエツ゚ヲロㇷ゚シㇼ“island with many capes”
- Russian · borrowed fromИтуру́п
- English todayIturup
From Russian Итуру́п (Iturúp), itself from Ainu エツ゚ヲロㇷ゚シㇼ (Etuworop-sir, “island with many capes”). Doublet of Etrof, from the Japanese rendition of the same Ainu toponym, Japanese 択捉 (Etorofu).
Etymology from Wiktionary, CC BY-SA 4.0.