Basic Guidelines For English Spellings
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Of a lorry, truck, etc.: designed so that most or all of the engine is located below rather than in front of the driver's compartment, with the vehicle usually having a flat vertical front. Abbreviated COE. Compare "cab-over [noun]", "cab-forward".
This design is relatively uncommon in North America and Australia, but predominant in Europe.
1930s; earliest use found in The New York Times. From cab + over + engine.