Eye line is a term used in the performing arts to refer to the imaginary line that an actor looks at when delivering a line of dialogue. It is also known as the 'fourth wall' and is used to create a sense of realism and connection between the actor and the audience. The crossword solution for the term eye line is 'BROW', which refers to the area of the face above the eyes. This area is often used to express emotion and can be used to help an actor convey their character's feelings.