Covering a very large area or having a wide range; or the action of using a broom to clean.
From Old English 'swapan' meaning to sweep or brush. The '-ing' suffix creates both the verb form (the action) and adjective (describing something broad in scope). The figurative sense of 'wide-ranging' developed in the 1600s.
Interestingly, 'sweeping' generalizations became a formal logical fallacy term because we literally 'sweep' too much together without examining details—the metaphor stuck because it perfectly captures careless overgeneralization.
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