Having the form, structure, or characteristics of a stickleback or fish of the family Gasterosteidae.
From 'Gasterosteidae' + Latin '-iform' (having the shape or form of). Standard formation for describing organisms that resemble members of a specific family without necessarily being classified within it.
The '-iform' suffix is a taxonomist's way of saying 'looks like this thing'—so if a fossil fish was gasterosteiform, it meant scientists found a fish that had the key belly-bone stickleback look even if it predated the whole modern family.
Complete word intelligence in one call. Free tier — 50 lookups/day.