Origin of -eous; from Classical Latin -eus + -ous
Having the nature of; resembling: gaseous.
Origin of -eousMiddle English, from Old French -eux, -eus (from Latin -&omacron;sus) and from Latin -eus.
From earlier -uous, alteration of -wose, -wos, a variant of -wise, from Middle English -wise, -wis, -wys, from Old English -wīs (“-wise”). More at -wise.