Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
arvālis, e, adj. [arvum], pertaining to a cultivated field; hence, Fratres Arvales, a college of twelve priests, who yearly made offerings to the field-Lares for the increase of the fruits of the field: Fratres Arvales dicti sunt, qui sacra publica faciunt propterea, ut fruges ferant arva, Varr. L. L. 5, § 85 Müll.; cf. Non. p. 560, 24 sq.; Müll. Etrusk. 2, pp. 91 and 105. Extant inscriptions show that this college of priests continued in existence until the fourth century; cf. Inscr. Orell. I. 388 sq.; 5054; 807; 840; 858; 903; 947; 961 al.