ˌsē(ˌ)näpˌterəˈdā(ˌ)lēz, ˌse- noun plural
Usage: capitalized
Etymology: New Latin, from coen- + Greek pterid-, pteris fern + New Latin -ales — more at pteris
: an order of extinct Devonian and Carboniferous ferns that is usually considered as part of or coextensive with the subclass Primofilices and that has both simple and pinnate leaves with the latter having pinnae at an angle to the plane of the leaf blade