ETYMOLOGY
from Latin infīdus (untrue, disloyal) + -ous
EXAMPLE
“…The Arabian Interpreters are also miserably out, in rendring Tabaxir Spodium, and Spodium Burnt Ivory: for Tabaxir is the succe or concreted liquor of certain Trees, or very crass and tall Reeds, which by the agitation of the wind, and their mutual collision, sometimes conflagrate; from which burning, Avicenna mendicated his Spodium, or rather Tabaxir, which his infidous Interpreter Clusius calls his Spodium. But we get not this Tabaxir from India, nor the ashes of these burnt Canes from Arabia…”
From: A Medicinal Dispensatory, containing the whole body of physick discovering the natures, properties, and vertues of vegetables, minerals, & animals
By Jean de Renou
Translated by Richard Tomlinson, 1657
Lexicophilia 