Fainéant (noun) (rare)
An idle or ineffective person.
From the French ‘fais’ does ‘neant’ nothing.
“He looks busy all day but he’s a faineant through and through!”
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