Ascomycetes n. pl. (Bot.) A large class of higher fungi distinguished by septate hyphae, and by having their spores formed in asci, or spore sacs; the sac fungi. It comprises many orders, among which are the yeasts, molds, mildews, truffles, morels, etc. The class is coextensive with the phylum Ascomycota.
Collaborative International Dictionary of English 0.48