1An extra wheel for a four-wheeled vehicle.

1. 1.1informal A superfluous person or thing.
   〈非正式〉多余的人（或物），累赘
   Example sentencesExamples

   • We were at the mall and I was trailing behind the two couples going in and out of the conversation and feeling very much like a fifth wheel.
   • Months of double dates with me as the fifth wheel flashed before my eyes.
   • In 1959, when he died, Bloch's work was pretty much a fifth wheel in the wider classical-music world.
   • Though they tried to include me in their activities I generally declined their invitations not wanting to be a third wheel or a fifth wheel or a seventh wheel.
   • I remembered The Duo hardly ever had double dates together, since Devon and Jemma thought I would feel left out if I was not invited, and I would be the fifth wheel if I joined.
   • It was nice to feel like we were a part of the program instead of a fifth wheel and a pain in the neck.
   • I was always the third wheel - or rather, fifth wheel.
   • Josh, his date, Jessica, Mary and Jason all went as a group of friends, but the whole night Jessica felt like the fifth wheel.
   • Oh come on, we still need to find out who the fifth wheel is.
   • As a bloke in the delivery suite, you always feel like a fifth wheel anyway.
   • Whenever I go out with my friends, I feel like the fifth wheel.
   • I was now the fifth wheel, and I hated being the fifth wheel.
   • I grew tired of being the fifth wheel so I got up and went into my room to study.
   • I felt like a fifth wheel and I hated it, but I didn't say anything.
   • Chris had remarried, and Gill felt like a fifth wheel while living with him, his new wife, and his two stepchildren.
   • I could have gone by myself, but it wouldn't have been a smart thing to do because two couples and the fifth wheel usually don't work out too well to begin with.
   • Don't they become fifth wheels, spinning pointlessly in relation to the processes responsible for human action?
   • Socially, I don't think it's impacted me - my friends are good about not making me the fifth wheel, it's not keeping me from jobs or anything.
   • Judge George Hatch always felt like a fifth wheel when he was invited to join his four friends.
   • Armed with a meat and cheese tray and some chips and dip, she was determined to make it through the day, however, even if it meant being a fifth wheel and having to see Nolan and Kari together.

2A coupling between a trailer and a vehicle used for towing.

1. 2.1also fifth-wheel trailer A trailer with accommodations for camping out.
   （有生活起居设施的）野营挂车
   Example sentencesExamples

   • We'd buy a large pickup truck and a fifth-wheel trailer and would travel the United States indefinitely - a retirement many couples enjoy immensely.
   • But we also have what we call towable products, travel trailers, fifth-wheel trailers.
   • Kaliska headed back out to the trailer area where multiple trailers and fifth wheels and tents were set up.
   • Then I camped with a tent and a sleeping bag, now we stay in a 28 ft. fifth wheel trailer which also has a slide out dining room.
   • Bryan's father, my mom's brother and his wife had left the week before Christmas to drive to Florida in their fifth wheel and new trailer.
   • On the other hand, my parents own a fifth-wheel trailer.
   • For instance, the F - 350 is once again the class leader with a new tow limit of up to 17,000 lb for a fifth wheel trailer and 15,000 lb for a conventional one.
   • In February 2003, my wife and I began our year as usual by hooking up our fifth-wheel trailer and travelling south for some winter sun.
   • When Ruth and I hit the road from 1992 to 1994 in our 3/4 ton Chevy truck and our fifth wheel trailer, with the blessings of the Steering Committee we became roving ambassadors for OLOC.
   • Hitch-mounted trailers and even gooseneck and fifth-wheel trailers follow the vehicle path much more closely than with conventional two-wheel steering.
   • King of the Road has a web site that shows LTM's patio deck which slides under the fifth wheel trailer when not in use, and slides out when you need a place to sit that's up and out of the mud and dirt.
   • Thompson, 40, got off to a late start this season after the purchase of a new truck and fifth wheel trailer, but he has since been racing at Division 5 events.
   • We lived in a 26 foot, fifth wheel, RV trailer when Henry died.
   • He also has a 1971 Fury, a dragster frame and a fifth wheel trailer.
2. 2.2historical A horizontal turntable over the front axle of a carriage as an extra support to prevent it tipping.
   〈史〉（马车前车轴上的）转向轮