Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Tănăquil, īlis, f., the proud, imperious wife of the elder Tarquin, Liv. 1, 34; Plin. 36, 27, 70, § 204.
Hence, as an appellative, for a domineering, ambitious woman, Juv. 6, 566; Aus. Ep. 23, 31.