noun

a chain or garland of flowers, leaves, or ribbons, hung in a curve as a decoration.

garland,chain,lei,swathe,swag,wreath,chaplet,loop

verb

adorn (a place) with chains, garlands, or other decorations.

the staffroom was festooned with balloons and streamers

decorate,adorn,ornament,trim,dress up,array,deck (out),hang,loop,thread,cover,drape,swathe,garland,wreathe,bedeck,beribbon,bespangle,do up,do out,get up,tart up,trick out,bedizen,furbelow,caparison,befrill,bejewel