From Wiktionary, the free dictionary

From flat +‎ bed.

• (General American) IPA^(key): /ˈflætˌbɛd/

flatbed (plural flatbeds)

1. An open freight vehicle with no sides, designed to carry heavy or outsized loads.
2. A railway freight car with no sides; a flatcar.

   • 2021 December 29, “Network News: DRS acquires compact electric shunter”, in RAIL, number 947, page 14, photo caption:

     The Rotrac E2 shunter was built by German manufacturer Zwiehoff and has been subject to a 14-month trial to prove it can replace diesel traction for moving flatbed wagons in and out of the depot.

3. Clipping of flatbed trolley.
4. (computing) A document scanner with a flat bed.

• flat bed
• flat-bed

• flatbed lorry
• flatbed editor
• flatbed truck

flatbed (not comparable)

1. Having a flat bed.

   I can't scan the whole document quickly because I only have a flatbed scanner.

   The accident left the contents of a flatbed trailer scattered across all three lanes.

flatbed (third-person singular simple present flatbeds, present participle flatbedding, simple past and past participle flatbedded)

1. To transport by flatbed.

   • 2000, Paullina Simons, The Bronze Horseman, →ISBN:

     Tatiana went from working the pulley that lifted the treadless tank and placed it on tread, to painting the red star on a finished tank ready to be flatbedded and put into production.

   • 2011 -, James Hayman, The Cutting, →ISBN:

     'Well, we won't know about prints till we can flatbed his SUV back to Middle Street and check, but given he left the car in a hurry, my guess is we'll find something, maybe quite a lot.

   • 2012, Rus Bradburd, Make It, Take It, →ISBN, page 23:

     “I'm going to have to flatbed this vehicle,” Larry said with an air of importance that irritated Pytel.

• The verb "to flatbed" is most commonly used when referring to the transportation of a vehicle, to make it clear that the vehicle is not being driven.