Other forms: dishearteningly
Something disheartening causes you to lose your confidence or enthusiasm. It's disheartening when your basketball team loses four games in a row.
Breaking disheartening down to its parts, you can see the dis- prefix, meaning "not" or "take away," and the figurative heart, "good feelings or courage." While a heartening message from your pen pal cheers you up, anything disheartening does the opposite. A disheartening grade on your big English paper brings you down, and disheartening news can make your whole family feel a little depressed. If it's disheartening, it's a bummer.