In the book, "precision of language" means using the correct words to convey the exact thought the speaker intends to communicate. In other words, by using precise language, the speaker can communicate the actual thought and not something that is close to the thought. The narrator even notes that:

the reason for precision of language was to ensure that unintentional lies were never uttered.

In the society of The Giver where everything is planned, precise language is expected from all citizens to avoid unintentional mistakes or accidents in speech. In fact, mistakes in general are not tolerated, including sloppy speech. The author provides a good example when Jonas says something that is not precise.

One day in school, Jonas exaggerates. Just before the class lunch break, he says that he is "starving.” Immediately, he is taken aside and chided for this statement or “lie.” He is told that since he was not actually starving, but merely “hungry,” he was speaking a lie. Even though the lie was unintentional, it is still not acceptable.

Viewing this rule through the lens of our more tolerant society, the reaction to Jonas' statement appears to be too harsh. It seems clear that most people would understand that Jonas was not really starving. His use of the word was intended to convey that he was very hungry and was anxious for the lunch break so that he could eat. However, in Jonas’ dystopian planned society, there is no allowance for exaggeration or what the society deems imprecise speech.

In Lois Lowry’s The Giver, precision of language is an important concept to the members of the community. The community adheres to the ideal of precision of language which leaves the meaning of many words, such as those that describe emotions, vague and devoid of meaning. Each night, Jonas’ family unit participates in a “telling of feelings” ritual despite the fact that they gave up their feelings. This can be seen in chapter one when Lily describes her anger at another child who did not understand the rituals at Daycare.

"I felt very angry this afternoon," Lily announced. "My Childcare group was at the play area, and we had a visiting group of Sevens, and they didn't obey the rules at all. One of them – a male; I don't know his name – kept going right to the front of the line for the slide, even though the rest of us were all waiting. I felt so angry at him. I made my hand into a fist, like this." She held up a clenched fist and the rest of the family smiled at her small defiant gesture.

Jonas realizes that precision of language did not allow for a meaning for the word anger. Words such as love, anger, and happiness are too vague, therefore devoid of meaning in this society. Jonas’ father is the “Nurturer” to young children but he both cares for them and kills them.

The idea of precision of language is supposed to prevent anyone from telling lies. Jonas realizes that this is a form of control because the whole community is actually a lie and a way to create a “non-human” society. The people function according to a set of rituals that are based on precision of language that is devoid of meaning for words that describe emotion, including the notion of love. A society that defines love could be considered dangerous.

In Lois Lowry's society of The Giver, "precision of language" is nothing short of thought control as it prohibits the free expression of emotion. For, emotional expression often leads to discontent and awareness of differences. During his training, Jonas is told,

"Our people made that choice, the choice to go to Sameness. Before my time, before the previous time, back and back and back. ....We gained control of many things. But we had to let go of others." (Ch.12)

And, as his instruction continues, Jonas realizes 

[He] found that he was often angry...that they were satisfied with their lives which had none of the vibrance his own was taking on. (Ch.13)

The limitations placed upon the expression of people's emotions through "precision of language" results in the suppression of what composes an individual's humanness and unique soul. Therefore, just as color has been eliminated from the sight of the members of the community, so too have the shades of feeling been eradicated with "precision of language" in order that no discontent may be given expression in the controlled society.

The community in The Giver placed great value upon precision in communication - choosing words that conveyed easily understood and measured meanings. In the community's drive to achieve Sameness, it became vital that everyone understood precisely and exactly what was meant by everything that was said by someone else.

This is why Jonas's parents reacted as they did when Jonas asked if they loved him.

There was an awkward silence for a moment. Then Father gave a little chuckle. “Jonas. You, of all people. Precision of language, please!”

"Love" is an emotion. It is a word that can mean many different things to different people. This made it completely unacceptable for use in the community that could not deal with variety or difference.