Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
1. stīrĭa, ae, f. [cf. stilla; Engl. tear], a frozen drop; an ice-drop, ice-drop, icicle (poet. and in post-Aug. prose), Verg. G. 3, 366; so too Plin. 34, 12, 32, § 124; Mart. 7, 37, 5; Claud. B. Get. 327; Tert. Pall. 4.