ETYMOLOGY
from Latin ferocientem, present participle of ferocire (to be fierce) , from ferox (fierce)
EXAMPLE
“…November 18 about four in the morning a lamentable fire seised upon the Lord Wimbletons house in the Strand, it being then the lodging of the States Lieger Ambassador, which consumed and demolisht it with all the rich furniture and utensils to the ground; so ferocient and impetuous it was, as the Ambassadour, his wife and children hardly, though half naked, escaped; all their other apparel, Jewels, money, &c. yea even the Commission it self perisht in the combustion…“
From: The Reign of King Charles
By Hamon L’Estrange, 1655
Lexicophilia 