Shunning the light (of a creature).
Mid 17th century: from Latin lucifugus (from lux, luc- ‘light’ + fugere ‘to fly’) + -ous.
“We don’t see him during the day time, but he’s in his garden at night. It’s as though he’s lucifugous.”
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