Early 17th century: from Old Norse and Swedish troll, Danish trold. The first English use is from Shetland; the term was adopted more widely into English in the mid 19th century.

• In Scandinavian folklore, trolls are ugly giants or dwarfs that usually live in caves. The word entered English in the early 17th century, and has no connection with the much earlier troll ‘to fish by trailing a baited line along behind a boat’, or ‘to search’. Nowadays internet users also ‘troll’, or send a provocative email or newsgroup posting to provoke an angry response or flame mail. The origin of this troll is uncertain—its original sense was ‘to stroll, roll’, which might be connected to old French troller ‘to wander here and there’, or early German trollen ‘to stroll’. It is probably the origin of trolley (early 19th century), originally a kind of low cart used for transporting goods such as fruit, vegetables, or fish. The trolley in off your trolley, is a kind of pulley that runs along an overhead track and transmits power to drive a tram. If a tram becomes disconnected from the pulley, it is no longer under control. A similar idea is found in to go off the rails, meaning ‘to start behaving in an uncontrolled or unacceptable way’, from the image of a train leaving the tracks or being derailed.

Late Middle English (in the sense 'stroll, roll'): origin uncertain; compare with Old French troller 'wander here and there (in search of game)' and Middle High German trollen 'stroll'. The computing senses (first recorded in 1992) are probably influenced by troll¹.