Lacking interest or excitement; boring. The lecture was so dull that half the audience fell asleep.
Lacking brightness, vividness, or sheen. The sky was a dull gray, promising rain later in the day.
Not sharp or pointed; blunt. The knife was too dull to cut through the tomato.
Not intense or acute; lacking in force or intensity. She felt a dull ache in her shoulder after the workout.
Slow to understand; lacking quickness of perception or intellect. Even as a child, he was considered dull compared to his quick-witted sister.