pro·actinomyces \(|)prō+\noun Etymology: New Latin, from pro- (I) + Actinomyces 1.capitalized, in some classifications: a genus comprising various actinomycetes that are now usually included in Nocardia 2.pluralproactinomycetesalsoproactinomyces: any actinomycete now or formerly included in the genus Proactinomyces