One who lodges temporarily in a hut or camp, especially who sleeps in a wilderness for recreation. [1913 Webster]
A person who stays at a summer camp or day camp. [PJC]
A vehicle, such as a small truck, or a pickup truck with a hood over the back, equipped for convenience while camping out. [PJC]

happy camper a person who is pleased with the situation in which s/he finds him/herself. Often used ironically or in understatement, especially in the negative; as, the passengers left behind on the island were not a bunch of happy campers.

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OXFORD DICTIONARY

camper, n.
1 a person who camps out or lives temporarily in a tent, hut, etc., esp. on holiday.
2 a large motor vehicle with accommodation for camping out.

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THESAURUS

camper

adventurer, alpinist, astronaut, camp trailer, caravan, climber, comers and goers, commuter, cosmopolite, cruiser, excursionist, explorer, fare, globe-girdler, globe-trotter, goer, hajji, house trailer, jet set, jet-setter, journeyer, mariner, mobile home, mountaineer, palmer, passenger, passerby, pathfinder, pilgrim, pioneer, rubberneck, rubbernecker, sailor, semitrailer, sightseer, straphanger, tourer, tourist, trail car, trailblazer, trailbreaker, trailer, trailer camp, trailer court, trailer park, transient, traveler, trekker, tripper, truck trailer, viator, visiting fireman, voortrekker, voyager, voyageur, wayfarer, world-traveler

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