Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
sabūcus, i, v. sambucus.
2. sambūcus (săbūcus, ap. Ser. Samm.), i, f., an elder-tree, Plin. 16, 18, 30, § 74; 17, 20, 34, § 151 al.; Ser. Samm. 7, 100; 19, 337; 27, 503 al.
Hence, sambū-cum, i, n., the fruit of the elder, elder-berries, Scrib. Comp. 160.