Marked is an adjective meaning “clear” or “noticeable.” Filling your living room with pictures of pandas will show your marked appreciation for all things panda.
The adjective marked can have several senses. In addition to meaning “very noticeable,” it can be used in relation to the noun mark, as in “to show a mark.” You may have also heard the expression a “marked man.” Marked in this sense means to have been chosen for punishment or a bad ending. Trip your opponent in this year’s field day sack race, and you will likely find yourself a marked man at the next contest.