To be always optimistic regardless of the facts.
From the name of the tutor and philosopher in Voltaire’s Candide (1759)
“He’s such a pangloss, he’d see he positive in anything.”
“Her panglossian thinking always got us 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