mid-15c., "fit out, equip, to provision" (a castle, ship, person); "provide (soldiers)," from Old French furniss-/forniss-, present participle stem of furnir/fornir "accomplish, carry out; equip, fit out; provide" (12c.), from Vulgar Latin *fornire, alteration of *fromire, from West Germanic *frumjan "forward movement, advancement" (source also of Old High German frumjan "to do, execute, provide"), from Proto-Germanic *fram- "forwards" (see from). General meaning "to provide" (something) is from 1520s; specifically "provide furniture for a room or house" from 1640s. Related: Furnished; furnishing.
<a href="https://www.etymonline.com/word/furnishings">Etymology of furnishings by etymonline</a>
Harper, D. (n.d.). Etymology of furnishings. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/furnishings