riches (n.)

"valued possessions, money, property," c. 1200, modified from richesse (12c.), a singular form misunderstood as a plural, from Old French richesse, richece "wealth, opulence, splendor, magnificence," from riche (see rich (adj.)). The Old French suffix -esse is from Latin -itia, added to adjectives to form nouns of quality (compare fortress).