Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
lībum (lībus, m., Nigid. ap. Non. 211, 31), i, n. [libo; cf. Varr. L. L. 4, 22], a cake, pancake of meal, made with milk or oil, and spread with honey, Cato, R. R. 75: rustica liba, Ov. F. 3, 670: adorea liba per herbam Subiciunt epulis, Verg. A. 7, 109; Ov. F. 3, 761: plena domus libis venalibus, Juv. 3, 187.
Often used in offerings to the gods: liba absoluta esse et rem divinam paratam, Varr. R. R. 2, 8, 1: suum Baccho dicemus honorem, … et liba feremus, Verg. G. 2, 394; Tib. 1, 7, 54; 1, 10, 23; Hor. Ep. 1, 10, 10: melle pater (Bacchus) fruitur, liboque infusa calenti Jure repertori candida mella damus, Ov. F. 3, 761: haec te liba, Priape, quot annis Exspectare sat est, Verg. E. 7, 33. It was customary to offer a cake to the gods on one’s birthday, Juv. 16, 38.
Hence, quinquagesima liba, a cake offered to the gods on one’s fiftieth birthday, Mart. 10, 24, 4.
In masc.: faciat libos quatuor, Nigid. ap. Non. 211, 31.