"Originally: †designating a fern in which the sori arise as a continuous mass covering the lower surface of the fertile frond, typified by, but not exclusive to, the genus Acrostichum (family Polypodiaceae); characteristic of such a fern ( obsolete ). Now: specifically designating or relating to sori with this pattern of distribution", Mid 19th cent.; earliest use found in Hooker's Journal Botany. From scientific Latin Acrostichum, genus name + -oid.[acrostichoid etymology, acrostichoid origin, 英语词源]