cab (n.)

1826, "light, two- or four-wheeled horse-drawn carriage," a colloquial London shortening of cabriolet, a type of covered horse-drawn carriage (1763), from French cabriolet (18c.), diminutive of cabriole "a leap, a caper," earlier capriole (16c.), from Italian capriola "a caper, frisk, leap," literally "a leap like that of a kid goat," from capriola "a kid, a fawn," from Latin capreolus "wild goat, roebuck," from caper, capri "he-goat, buck," from PIE *kap-ro- "he-goat, buck" (source also of Old Irish gabor, Welsh gafr, Old English hæfr, Old Norse hafr "he-goat"). The carriages were noted for their springy suspensions.

Originally a passenger-vehicle drawn by two or four horses; it was introduced into London from Paris in 1820. Extended to hansoms and other types of carriages, then extended to similar-looking parts of locomotives (1851). Applied especially to public horse carriages, then to automobiles-for-hire (1899) when these began to replace them.

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Definitions of cab from WordNet
cab (n.)
a compartment at the front of a motor vehicle or locomotive where driver sits;
cab (n.)
small two-wheeled horse-drawn carriage; with two seats and a folding hood;
Synonyms: cabriolet
cab (n.)
a car driven by a person whose job is to take passengers where they want to go in exchange for money;
Synonyms: hack / taxi / taxicab
cab (v.)
ride in a taxicab;
Synonyms: taxi