It’s one of a select class of English words, including crapulent and formicate, that are guaranteed to mislead readers and raise a giggle among children of all ages.
I’m reminded of a wonderful monologue that the British comedy actor Ronnie Barker gave many years ago on a television show called The Two Ronnies. In a sketch peppered with real and fictional Cockney rhyming slang he claimed to have encountered a small brown Richard the Third on the ground, which he picked up and put on a wall out of the way. The story ends with it flying off.
There’s a good reason for my bringing that up, apart from wanting to share a memory, because turdiform is an adjective that refers to birds of the thrush family. It comes from Latin turdus for one of the European thrushes, probably the song thrush or mistle thrush (the latter having been given that name because it was noted for eating berries, particularly those of the mistletoe).
Turdiform is found exclusively in old-time ornithological works. It has always been specialist and technical; its appearances lie mainly in the period from 1870 to 1910 and it is obsolete. We may guess that a certain fastidiousness on the part of writers has led to their expelling it from their vocabulary.
However, the genus Turdus for the thrushes survives. Members include Turdus migratorius, the American Robin (the European robin used to be thought a thrush but is now in a different genus) and Turdus maximus, the Tibetan blackbird.