psi·lo·ta·ce·ae \ˌsīlōˈtāsēˌē\noun plural Usage: capitalized Etymology: New Latin, from Psilotum, type genus + -aceae : a family of plants that are usually placed in order Psilotales and are characterized by nearly naked stems, minute scalelike leaves, and 2- or 3-celled sporangia — compare psilotum, tmesipteris • psi·lo·ta·ceous\| ̷ ̷ ̷ ̷|tāshəs\adjective