Early 18th century; earliest use found in John Harris (c1666–1719), writer and lecturer on science. From pyramid + -oid, after post-classical Latin pyramidoides.
Definition of pyramidoid in US English:
pyramidoid
nounpɪˈramɪdɔɪd
Geometry
A solid figure resembling a pyramid. Now rare.
Origin
Early 18th century; earliest use found in John Harris (c1666–1719), writer and lecturer on science. From pyramid + -oid, after post-classical Latin pyramidoides.