ˌpedēˈastrəm, ˌpēd- noun
Usage: capitalized
Etymology: New Latin, from pedi- (II) + Greek astron star — more at star
: a genus of free-floating green algae (family Hydrodictyaceae) that have flat platelike colonies of two or more polygonal cells with the marginal cells usually differing in shape and having usually two projections of the cell wall