Scout’s real name is Jean Lousie Finch—but no one except those who wish to impose social expectations on Scout ever refers to her by her given name. Miss Caroline (her teacher), Miss Maudie, and Aunt Alexandra are the three main offenders who call Scout “Jean Louise” and nothing else. Scout’s nickname is a symbol of her status as a “tomboy” and her unwillingness to live up to southern social standards for little girls.
While we don’t know who gave Scout her nickname or exactly why she is called Scout, we can infer from a survey of the text. Scout is a word that typically describes someone in an army or military setting that is sent out to observe, question, and report on the movement of an enemy. Scout in the book fits this nickname because she is continuously observing the goings on in the world, and she asks seemingly impertinent questions because of her age. Her ability to navigate the world of adults, exposing things like hypocrisy and the nature of good and evil, is a unique trait, but it helps us see why she would be called Scout.
An example from the text of when Scout is observing and questioning the actions or thoughts of another character happens when Scout asks Jem a question about a lesson she has in Mrs. Gates's classroom:
Well, coming out of the courthouse that night Miss Gates was—she was goin' down the steps in front of us, you musta not seen her—she was talking with Miss Stephanie Crawford. I heard her say it's time somebody taught 'em a lesson, they were gettin' way above themselves, an' the next thing they think they can do is marry us. Jem, how can you hate Hitler so bad an' then turn around and be ugly about folks right at home—" (chapter 26)
Scout, despite only being in third grade, observes that Mrs. Gates is a hypocrite in her thinking. The concept of hypocrisy causes Scout a lot of a difficulty because it doesn’t make sense to her how someone can hold such contradictory ideas at the same time. This instance demonstrates why Scout’s name is fitting, why she was probably given the nickname, and how her questions and observations help us explore the concepts in the book.