A chassis is the frame everything else in a vehicle is bolted to. A steel chassis, a chassis number, the chassis flexed.
Most modern cars have no separate one — the body and frame are welded into a single shell — but lorries and off-road vehicles keep a real chassis for strength. The word is the same in the singular and the plural, and the final s is silent.
1nounchassisThe frame everything else in a vehicle is bolted to.
“The car's body was badly damaged, but the chassis underneath was still straight.”
chassis is a frame.
French chassis means a frame, from chasse, a case, from Latin capsa, a box. Case and chase are relatives.
Proto-Indo-European
*kap-
Latin
capsa — case
French
châssis
English, today
chassis
French châssis, from châsse, from Latin capsa (“case”).
Etymology from Wiktionary, CC BY-SA