Of interest re nugatory is its descent from a word meaning jokes or trifles. (Latin, nugae). Currently meaning without force or validity.

I am completely undone by arctophile. I'ld have thought it was someone fond of northern climes, but lo and behold the word in fact comes from t he same root by means of the Great Bear constellation:Alteration (influenced by Latin arcticus) of Middle English artic, northern, from Medieval Latin articus, from Latin arcticus, from Greek arktikos, from arktos, bear, the northern constellation Ursa Major .

As to unusual words I offer baccaceous ( like a berry; bearing berries). And, for other purposes altogether, babuina, female baboon.

For hours of interesting exploration I suggest the Dictionary of Difficult Words found at this site.

Regards,

A