Wiktionary
n. (context mycology English) Any fungus with a fruiting body whose hymenophore develops either unenclosed or enclosed only with a velum.
Wikipedia
Hymenomycetes was the largest class of fungi within the phylum Basidiomycota, but the term is no longer taxonomically relevant. Many familiar fungi belong to this class, including bracket fungi and toadstools. This class contains the orders Agaricales, Boletales, and Russulales.
Formerly a taxonomic group of basidiomycetes, now understood as polyphyletic assemblage of basidiomycetes, the term refers to fungi with fruit bodies whose hymenophore develops either not enclosed or only so with a veil ( velum), which is called a gymnocarpic or hemiangiocarpic ontogeny, respectively. Puffballs, on the other hand, have gasterocarpic development (hymenophore enclosed).
Usage examples of "hymenomycete".
The third class, Hymenomycetes, or Membrane fungi, has been described, but there remain two other groups of which we will now speak more fully.
In the family called Hymenomycetes there are mixed with these, and closely packed together, one-celled sterile structures named cystidia.