“+ˌ- noun
also meso·spo·ri·um | ̷ ̷ ̷ ̷|spōrēəm
( plural mesospores -z ; or mesospo·ria -ōrēə)
Etymology: mesospore from mes- + -spore; mesosporium from New Latin, from mes- + -sporium
1. : the middle coat of a spore that has three coats
2. : a one-celled spore found among the compound teliospores of some rusts (as members of the genus Puccinia )