"circular saw," 1849, American English, from buzz (v.) + saw (n.). So called from the sound it makes when in operation.
Entries linking to buzz-saw
buzz v.
late 15c. (buzzing is from late 14c.), echoic of bees and other insects. The aviation sense of "fly low and close" is by 1941 (see buzz (n.)). Related: Buzzed. To buzz off "go away quickly" (1914) originally meant "to ring off on the telephone," from the use of buzzers to signal a call or message on old systems. As a command, it originally would have been telling someone to get off the line.
saw n.1
[toothed cutting tool] Middle English saue, from Old English sagu, from Proto-Germanic *sago "a cutting tool" (source also of Old English seax "knife," Old Norse sög, Norwegian sag, Danish sav, Swedish såg, Middle Dutch saghe, Dutch zaag, Old High German saga, German Säge "saw"), from PIE root *sek- "to cut" (source also of Latin secare "to cut").
In reference to its use as a musical instrument, by 1905. Saw-grass, the long, toothed grass found in the Southern U.S., is attested by 1822. The saw-fly (1773), destructive to plants, is so called for the construction of the insect's egg-depositing organ.