Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
1. dē-mĕto, messŭi, messum, 3, v. a., to mow, reap, cut off, gather, crop, harvest (class.). Usually of fruits: tempora demetendis fructibus et percipiendis accommodata, Cic. de Sen. 19, 70; cf. id. N. D. 2, 62 fin.: hordeum, Cass. Hem. ap. Prisc. p. 903 P.: demesso frumento, * Caes. B. G. 4, 32, 4; so, frumentum, Liv. 34, 26: segetes, Tac. A. 14, 24; cf.: Galli armati alienos agros demetunt, Cic. Rep. 3, 9, 15: demessa est terra, Vulg. Apoc. 14. 16.
Less freq. (poet. or in post-Aug. prose) of other objects: pollice florem, to pluck off, Verg. A. 11, 68: favos, i. e. to cut out, take out, Col. 9, 15, 12: testes caudamque adultero (ferrum), Hor. S. 1, 2, 46; cf.: huic ense caput, to behead, Ov. M. 5, 104; and absol.: acies ferro demetit, Sil. 16, 102.