Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
prae-nosco, ĕre, v. a., to learn or become acquainted with beforehand, to foreknow (class.): futura, Cic. Div. 1, 38, 82; Suet. Ner. 56; Plin. 18, 24, 56, § 206: promissum sibi caelum, Ov. F. 3, 159: venturum caeli laborem, Stat. Th. 3, 490: rerum fata, Sil. 3, 7: omina, id. 16, 124; Vulg. Gen. 15, 13 (but in Plaut. As. 1, 1, 46, the correct reading is: in pretio sumus, acc. to Fleck. and Ussing).