oscillum

Latin

Etymology 1

A double diminutive from ōs (“mouth; face”), analyzable as ōs +‎ -culum +‎ -lum or as ōsculum (“little mouth”) (mostly attested in the derived sense 'kiss') +‎ -lum.

Pronunciation

(Classical Latin) IPA^(key): [oːsˈkɪl.lũː]
(modern Italianate Ecclesiastical) IPA^(key): [oʃˈʃil.lum]

Noun

ōscillum n (genitive ōscillī); second declension

a little cavity in the middle of leguminous fruits, where the germ sprouts forth
a little mask of Bacchus, hung from trees, so as to be easily moved by the wind

Declension

Second-declension noun (neuter).

	singular	plural
nominative	ōscillum	ōscilla
genitive	ōscillī	ōscillōrum
dative	ōscillō	ōscillīs
accusative	ōscillum	ōscilla
ablative	ōscillō	ōscillīs
vocative	ōscillum	ōscilla

Derived terms

ōscillō

Etymology 2

Traditionally taken as a nominal formation from obs- + an element *cillō (“to move”) + -um, the main semantic component of unknown origin.^[1] Whether the word decomposition into the above elements is even correct is also implicitly doubted by Ernout and Meillet.^[2] Note also similarities to vacillō (“to sway, waver”), also of unclear origin, as well as vague resemblance to celer (“fast, quick”).

Other theories identify ōscillum as a diminutive of ōs (“mouth”), as Bacchanal masks (resembling little mouths) would supposedly be hung from trees and swayed by the wind on them. This appears to be folk-etymological, however.