Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
1. Rūmīna (in some MSS. Rūmĭa), ae,f. [rumis, qs. she that offers her breast], a Roman goddess of nursing mothers, who was worshipped in a separate temple near the fig-tree under which Romulus and Remus had sucked the breast (rumis) of the shewolf, Varr. R. R. 2, 11, 5; id. ap. Non. 167, 30 sq. (v. the passages under rumis); Aug. Civ. Dei, 4, 11; 6, 19 fin.; 7, 11.
Hence,
2. Rūmĭna, ficus, v. 1. Rumina, B.