Definition
To give something back to someone, or to return a thing to where it belongs.
Example
借りた本を友達に返した。
Show translation
I returned the book I borrowed to my friend.
Etymology
返す combines the kanji 返 (return, turn back), which itself traces to the Chinese character 返 (fǎn), meaning "to go back" or "to turn over." The verb ending -す (-su) is a causative-like suffix in classical Japanese that gives it a transitive sense: to cause something to go back.
Cultural note
In Japanese culture, the idea of returning things — whether borrowed objects, favors, or greetings — carries significant social weight. The related concept of 恩返し (ongaeshi, "returning a kindness") reflects a deep cultural value of reciprocity. Note that 返す can also mean "to reply" (言葉を返す, "to give words back") or even "to turn over" in some contexts, making it a versatile everyday verb. Don't confuse it with 帰る (kaeru, "to go home") — they sound similar but mean very different things!