Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
† rhythmos or -us, i, m., = ῤυθμός, symmetry, harmony, rhythm in music or speech, Mart. Cap. 9, § 967 sqq.; Varr. ap. Diom. p. 512 P.; Quint. 9, 4, 45 sq.; 51 sq.; 78; 109 (Cicero constantly has numerus instead of this word, which he writes only as Greek, Or. 20, 67; 51, 170).