listen means to pay attention to someone or something in order to hear what is being said, sung, played, etc.
The differences in the definitions tell us something about how each word is used. See and hear are usually used when you are talking about using the senses of sight and sound. On the other hand, look, watch, and listen are usually used when you are talking about paying attention to what you see or hear. Look is used to say something about where you are directing your attention. Watch is used to say that you are paying attention to something by looking at it for a period of time.
Now let's look at some example sentences using see, look, and watch:
Janet sees the sun coming in through the window and knows it is morning. [=she notices the sunlight with her eyes]
Janet looks towards the window because she wants to know if it is morning yet. [=she directs her attention towards the window]
Janet watches the sun come up in the morning. [=she pays attention to the rising sun for a period of time]
Janet sees that the game is on TV but she does not watch it with her sister. [=she notices the game on TV but she does not sit down and pay attention to it for a period of time]
Look up there! Do you see that airplane? [=direct your attention up there; do you notice that airplane?]
Now let's look at some example sentences using hear and listen:
Anthony hears music coming from his neighbor's house. [=he notices the music with his ears]
Anthony listens to music on his drive to work. [=he pays attention to the music coming from the radio]
The child hears his mother talking but he isn't listening to her. [=the child perceives the sound of his mother's voice but he is not paying attention to what she is saying]
We were listening for the sound of Amy's car in the driveway but we didn’t hear it. [=we were paying attention with our ears to notice if Amy pulled her car in the driveway but we didn't perceive that sound]
Use see and hear when you are talking about noticing something using the senses of sight and sound. Use look, watch, and listen when you are talking about directing your attention to, paying attention to, or focusing your mind on someone or something that is happening.