Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
hebdŏmăda, ae, f. [hebdomas], the number seven: annorum, librorum, Gell. 3, 10, 17.
Esp., = hebdomas, seven days, Gell. 3, 10, 14; Isid. de Nat. R. 3; Vulg. Gen. 29, 27 sq.; id. Exod. 34, 22 al.