means To scotch something is to decisively put an end to it or block it; as a noun, it's also a wedge or chock used to stop a wheel from rolling, and (capitalized) it names whisky from Scotland.

from Two different words sit under this one spelling. The 'put an end to it' sense comes from a late-medieval verb meaning to cut, gash, or notch — once written 'scocchen' and likely tied to Anglo-French and Old French words for slicing; Shakespeare uses 'scotch'd' for wounding. The 'wedge under a wheel' sense is of murky origin, possibly the same notching idea or possibly unrelated. The whisky and the people are a separate story entirely — 'Scotch' is simply a worn-down form of 'Scottish,' clipped through 'Scottisc' into 'Scotch.'