To whine means to complain in an annoying, high-pitched, or drawn-out way. When someone whines, they express disappointment in a way that grates on others, often repeating the same complaint over and over in a distinctive, irritating tone. A child might whine about being hungry, stretching out the words “I'm huuuungry” in that particular tone that makes parents wince.

The word also describes a high, prolonged sound. A dog might whine at the door when it wants to go outside, making that distinctive pleading noise. An old car engine might whine as it struggles uphill, creating a strained, high-pitched sound.

What makes whining different from regular complaining? It's the tone and the persistence. Someone stating “This math homework is really hard” is complaining. Someone saying “This is sooooo haaaard, I can't do it, why do we have to do this, it's impossible” in that characteristic drawn-out voice is whining.

People may whine when they feel powerless or want sympathy. A whiner is someone who complains this way habitually, and others may find it unpleasant to be around them.