Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
1. rŭbēta, ae, f. [rubus], a kind of venomous toad living among bramble-bushes, Juv. 1, 70; 6, 659; also, ranae, Plin. 8, 31, 48, § 110; 32, 5, 18, § 48; Prop. 3, 6 (4, 5), 27.