Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
prō̆pāgātor, ōris, m. [1. propago], a propagator; trop., an enlarger, extender (class.): provinciae propagator, Cic. Att. 8, 3, 3 (al. prorogator).
An epithet of Jupiter, as the enlarger of boundaries, App. de Mundo, p. 75, 10: ORBIS AC REI PUBLICAE ROMANAE, Inscr. Grut. 271, 4.