if you repeated this quote from Atticus to a child, they would still be completely clueless. It makes sense that he wanted to avoid giving a straightforward answer—rape is a pretty tough subject to discuss with your young daughter. However, it does make Atticus a bit of a hypocrite. He specifically told Jack earlier in the book to not to beat around the bush when a child asks you a question.

Scout first asks Calpurnia what rape is in chapter 12. Calpurnia, a wise woman, advises Scout to ask her father about the definition. Scout gets her chance to ask Atticus what rape is in chapter 14. Atticus's philosophy about answering children's questions is to be direct and not try to skirt the issue. So, being a wise man, he gives his young daughter the legal definition of rape in an effort to answer her, but also to avoid any graphic illustrations of the subject. Atticus's definition is as follows:

". . . rape was the carnal knowledge of a female by force and without consent" (135).

Scout's reaction is a bit funny because she pretends to understand what that means, but she doesn't. She just asks Atticus why Calpurnia didn't answer her when she first asked about rape. Unfortunately, Atticus doesn't get a chance to elaborate on the legal definition of rape because Aunt Alexandra pitches a fit about Scout having been at Calpurnia's church when she asked about rape. Hence, there is no more discussion about the definition of rape, for which Atticus must be relieved. The reason that the legal definition proves to be such a success is because Atticus doesn't flinch at the question; he confidently answers his daughter, which leaves no room for her to doubt him or to think that he is trying to avoid the subject.

As always, Atticus Finch tells it like it is when Scout demands to know what rape means in Harper Lee's novel, To Kill a Mockingbird. When Scout initially asks her Uncle Jack "what a whore-lady was," he beats around the bush. When Scout questions Calpurnia about rape, she instructs her to ask her father. Since Scout knows she can talk with Atticus about anything, she does.

    "What's rape?" I asked him that night.    Atticus looked around from behind his paper... He sighed, and said rape was carnal knowledge of a female by force and without consent.

Scout was less than enthused by Atticus' accurate definition, and drops the matter. But it only led to another argument between Atticus and Aunt Alexandra concerning Calpurnia's place in the Finch family.

At the beginning of chapter 14, of "To Kill a Mockingbird"  Scout remembers she has a question for Atticus.  "What's rape?" I asked him that night.  Atticus looked around from behind his paper.  He was in his chair by the window.  He sighed, and said rape was carnal knowledge of a female by force and without consent.  "Well if that's all it is why did Calpurnia dry me up when I asked her what it was?

Calpurnia did not think it was her place to explain the act of rape to Scout, so she left it up to Attitus.

Atticus tells Scout that rape is carnal knowledge of a female without her consent.

The trial of Tom Robinson is a rape trial.  Robinson was accused to raping a white woman, Mayella Ewell.  Scout is a little young to know about sex, let alone rape.  She asks Calpurnia what rape is, and Cal tells her that she has to ask her father.

Scout does ask Atticus, and she does not understand his definition.

He sighed, and said rape was carnal knowledge of a female by force and without consent.

“Well if that’s all it is why did Calpurnia dry me up when I asked her what it was?” (Ch. 14)

Scout has no idea what “carnal knowledge of a female” means, and probably does not understand the concept of consent.  "Carnal knowledge" means sex, and "consent" means the woman’s permission.  Atticus gave Scout a very wordy definition of forcing a woman to have sex, although rape is more like a man forcing himself on a woman.  It was an evasive answer.

Atticus is usually a pretty honest parent, and explains even difficult concepts to his children.  The definition he gave is interesting, because he had earlier told Jack not to be evasive in answering a child’s questions.  Jack told Atticus that Scout asked him what a whore-lady was.  Atticus asked Jack if he told her the truth.

“No, I told her about Lord Melbourne.”

“Jack! When a child asks you something, answer him, for goodness’ sake. But don’t make a production of it. Children are children, but they can spot an evasion quicker than adults, and evasion simply muddles ‘em. …” (Ch. 9)

Atticus did not follow his own advice in answering Scout’s question about rape. Perhaps he decided that she simply was not ready for the answer, and it was okay for her to be muddled a little while longer.

The issue of children hearing about rape comes up again at the trial.  There is a request for women and children to leave, but Judge Taylor does not grant it.  He basically says that people who brought their children to a rape trial should have known what was going to be discussed.

Scout and Jem have been exposed to many things because of their father Atticus' involvement with the trial of a black man accused of attacking a white woman. Scout has become curious about the term "rape" and has previously asked Calpernia what the word means. Calpernia referred Scout to Atticus who now must provide Scout with the information she seeks. 

As Atticus sits enjoying a few minutes of peace while reading, Scout interrupts his solitude with a question. Momentarily surprised, Atticus quickly recovers and responds to Scout's question about the meaning of the word rape. Atticus needed a definition suitable for a girl of Scout's age. He decided to provide Scout with a very basic, dictionary definition:

"Carnal knowledge of a female by force without consent."

This definition appeared to satisfy Scout and led to a conversation during which Scout told Atticus about having gone to church with Calpernia.

This is a good question. As Scout learns about the trial, she naturally asks what rape is, as Tom Robinson is on trial because of an alleged rape. So, at first Scout asks Calpurnia. Calpurnia feels uncomfortable in giving an answer, so she tells Scout to ask her father, Atticus. When Atticus finally comes home, Scout asks. Here is the dialogue: 

“What’s rape?” I asked him that night. Atticus looked around from behind his paper. He was in his chair by the window. As we grew older, Jem and I thought it generous to allow Atticus thirty minutes to himself after supper.

He sighed, and said rape was carnal knowledge of a female by force and without consent.

“Well if that’s all it is why did Calpurnia dry me up when I asked her what it was?”

As you can see Atticus was not able to deflect the question. So, he answered her in a direct manner. However, he spoke is a lawyerly way - carnal knowledge of a female by force without consent.

The funny thing is that Scout acted like she understood this definition, when in fact she had no clue what Atticus was saying. The point is that Atticus gave her an answer, but it was above Scout's head and understanding. In doing so, this answer satisfied Scout (she was given an answer), but also did not explain what rape was, as Scout was too young to understand. In the end, Scout and Atticus were satisfied. 

Atticus explains that "rape was carnal knowledge of a female by force and without consent" to Scout. It is an appropriate answer to give  her given her age, yet it doesn't fully explain the violence of such an act.