Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
3. vŏlo, ōnis, m. [1. volo], a volunteer, first applied to the slaves who, after the battle at Cannæ, were enrolled upon their own expressed desire to serve (cf. Liv. 22, 57, 11; Val. Max. 7, 6, 1): volones dicti sunt milites, qui post Cannensem cladem usque ad octo milia, cum essent servi, voluntarie se ad militiam obtulere, Paul. Diac. p. 370: volones, quia sponte hoc voluerunt, appellati, Macr. S. 1, 11, 30: vetus miles tironi, liber voloni sese exaequari sineret, Liv. 23, 35, 6; 23, 32, 1; Capitol. Anton. Phil. 21, 6; Macr. S. 1, 11, 30.