In botany, having the form of a petal; resembling petals in surface and shade, as specific bracts.
In zoology, resembling a leaf or petal; specifically, noting those heterogeneous ambulacra of some echinoderms, by the Clypeastroida, which the apical component is wide at the center and tapers to a place at the margin, where it joins the oral section. See cuts under ambulacrum, cake-urchin, and petalostichous.
How would you define petaloid?