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chassis

SHAS-ee /ˈʃæsi/

nounC1GRETOEFL

technical

The base structural frame and undercarriage of a heavy vehicle, onto which the body, engine, and tracks are built.

The underlying skeleton supporting all heavy mechanical stress, drive components, and structural loads.

The story behind the word. Borrowed from French 'châssis' (frame), derived from Vulgar Latin 'capsicius' (box-like frame), rooted in Latin 'capsa' (box). It originally referred to window sashes or picture frames before being adopted for automobile and machinery skeletons.

Word relationships

frame: 'Frame' is general, while 'chassis' specifically refers to the mechanical structural base of vehicles.
undercarriage: 'Undercarriage' often emphasizes the wheels, tracks, and suspension, whereas 'chassis' emphasizes the main load-bearing frame.

bodywork: 'Bodywork' refers to the outer cabin panels and superficial shell built upon the underlying chassis.

Commonly confused with

body: The chassis is the hidden structural frame underneath; the body is the visible upper shell housing passengers or controls.

Collocations

reinforced chassis
chassis frame
heavy-duty chassis
vehicle chassis

Example sentences

"Inspectors found a structural crack in the steel chassis of the haul truck caused by carrying excessive payloads." Equipment Repair
"The heavy tractor chassis was reinforced with thick alloy plates to withstand high torsion on rough construction terrain." Machinery Manufacturing

Memory hook

CHASSIS sounds like SHASS-EE: the structural frame sitting UNDER the seat. CHASSIS = the steel frame underneath.

When not to use

Do not confuse with the vehicle's bodywork, cab shell, or outer cosmetic panels.

Fun facts

The plural form of 'chassis' is spelled identically ('chassis'), but pronounced with a silent 's' at the end of the singular ('SHAS-ee') and a 'z' sound at the end of the plural ('SHAS-eez').