From ornothology, having a flat breastbone with a keel and so unable to fly.
Ratite describes flightless birds, as opposed to carinate birds, which are birds that have flight.
“The emu can run fast but it’s still ratite.”
The last stage of life; old age.
Senectitude comes from the Medieval Latin noun senectitūdō meaning “old age,” which in turn comes from Classical Latin senectūs, a derivative of the noun senex meaning “old man.” Senectitude entered English in the late 1700s, more precisely, in 1796 in Jonathan Swift’s Gulliver’s Travels