ETYMOLOGY
from Latin fidelis (faithful, loyal) + -ous
EXAMPLE
“…I ever (quoth Rhoxenor) have found thee cordially fidelious, doe but doe as thou hast indented, and expect what wealth, or honour thou canst covet, while Clodomer lives, and when his death, puts the Diadem upon my head, to be my only favourite…”
From: The Loves of Amandus and Sophronia
By Samuel Sheppard, 1650
Lexicophilia 