Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
dĕcem-pĕda, ae, f. [pes], a ten-foot measuring rod, Cic. Mil. 27, 74; id. Phil. 14, 4, 10; id. Ac. 2, 41, 126; * Hor. Od. 2, 15, 14 al.