出典:Wiktionary
Uncertain; apparently a diminutive in -ula from an unclear root. L&S and Gaffiot both propose rāvus (“grey”). If that is the correct etymology, the first vowel would presumably be /ā/, not /ă/. The apparent discrepancy in consonants would be explained by the fact that intervocalic /b/ and /w/ were merging to /β/ around the time that Pliny wrote his Historia naturalis (77 CE- the only work containing an attestation of rabuscula). As for the element *-usca, compare the endings of labrusca, atrusca.
First-declension noun.
| Case | Singular | Plural |
|---|---|---|
| Nominative | rabuscula | rabusculae |
| Genitive | rabusculae | rabusculārum |
| Dative | rabusculae | rabusculīs |
| Accusative | rabusculam | rabusculās |
| Ablative | rabusculā | rabusculīs |
| Vocative | rabuscula | rabusculae |