noun

a piece of cloth or similar material, typically oblong or square, attachable by one edge to a pole or rope and used as the symbol or emblem of a country or institution or as a decoration during public festivities.

the American flag

banner,standard,ensign,pennant,pennon,banderole,streamer,jack,bunting,colours,symbol,emblem,representation,figure,image,pendant,burgee,vexillum,gonfalon,guidon,labarum

verb

mark (an item) for attention or treatment in a specified way.

the spellcheck program flags any words that are not in its dictionary

indicate,identify,pick out,point out,mark,mark out,label,tab,tag,tick