frame rail

noun2

1. •
   Each of the two main longitudinal structural members of a body‑on‑frame vehicle, running parallel front to rear and supporting the chassis, to which cross‑members, suspension, drivetrain, and body are attached.

   • It has been proposed that the length of the middle, parallel portion of the sub-frame comes flush with the inner side of the lower flange of the main frame rail. — 1912
2. •
   A horizontal structural member of a furniture frame, typically joining the legs or vertical posts, providing support and rigidity; commonly found in tables, chairs, cabinets, and beds.

   • The frame rails must be firmly mortised into the legs to ensure stability. — 1901