"a whispering, a murmur," c. 1400, from Latin susurrationem (nominative susurratio), from past participle stem of susurrare "to hum, murmur," from susurrus "a murmur, whisper," a reduplication of the PIE imitative *swer- "to buzz, whisper" (source also of Sanskrit svarati "sounds, resounds," Greek syrinx "flute," Latin surdus "dull, mute," Old Church Slavonic svirati "to whistle," Lithuanian surma "pipe, shawm," German schwirren "to buzz," Old English swearm "a swarm").

1809, earlier as a medical Latin word in English, from Latin susurrus, literally "a humming, muttering, whispering" (see susurration).

Among the diseases of the ear, one of the most prevalent is the Paracusis imaginaria, to which both sexes are equally liable; and another variety of the same tribe, more frequent among female patients, called the Susurrus criticus, or Scandal-buzz. [The Lounger, Dec. 23, 1786]

"plainly illogical," 1550s, from French absurde (16c.), from Latin absurdus "out of tune, discordant;" figuratively "incongruous, foolish, silly, senseless," from ab- "off, away from," here perhaps an intensive prefix, + surdus "dull, deaf, mute," which is possibly from an imitative PIE root meaning "to buzz, whisper" (see susurration). Thus the basic sense is perhaps "out of tune," but de Vaan writes, "Since 'deaf' often has two semantic sides, viz. 'who cannot hear' and 'who is not heard,' ab-surdus can be explained as 'which is unheard of' ..." The modern English sense is the Latin figurative one, perhaps "out of harmony with reason or propriety." Related: Absurdly; absurdness.

"cloud of bees or other insects," Old English swearm "swarm, multitude," from Proto-Germanic *swarmaz (source also of Old Saxon, Middle Low German swarm, Danish sværm "a swarm," Swedish svärm, Middle Dutch swerm, Old High German swaram, German Schwarm "swarm;" Old Norse svarmr "tumult"), by Watkins, etc., derived from PIE imitative root *swer- "to buzz, whisper" (see susurration) on notion of humming sound, and thus probably originally of bees. But OED suggests possible connection with base of swerve and ground sense of "agitated, confused, or deflected motion." General sense "large, dense throng" is from early 15c.