featherless biped
A human being, as said by Plato, until Diogenes "persuaded" him into changing it to a featherless biped with broad, flat nails.
Plato said that a human was a featherless biped.
In response, Diogenes plucked a chicken and gave it to Plato, saying "Here is Plato's man!"
Plato then changed it to featherless biped with broad, flat nails