“To bite your lip” is to refrain from speaking. It can also be applied to restricting any emotional reaction in a social situation. The term is applied as a notion, “I had to bite my lip today,” or as a command, “Bite your lip!” It is used when information is known that would disrupt a social situation, but should not be revealed.
It is a figurative phrase or idiom that has a literal origin. A person would bite his or her lip in order to keep his or her mouth closed. It then developed into its non-literal form to represent restraint and stoicism. “To bite your tongue” is similar in notion, but its modern use is to prevent a person from saying something nasty.
The phrase “to bite your lip” conveys a pressing need in one or more people to reveal something. This can be a truth, as opposed to a lie being told, or a different opinion. Rather than being allowed to enter into a free discourse, the individual either feels or is told to keep quiet. This suggests that their information will cause harm to one or more individuals present or will cause other problems.
Any information or feelings that need to be hidden vary from case to case. For example, if someone is at a wedding and feels the need to keep quiet or is told to “bite your lip,” there can be several reasons. First, there is the hidden information or feelings. The person may love one of those getting married or they may know one of them has lied about something or is having an affair. Second, the person is aware or made aware of the consequences of her action, which would be to ruin the entire wedding and possibly cause the couple to split.
In the example given, the person bit her lip in order to preserve social harmony. She also protected somebody else’s feelings. A rational argument can be made that she also protected a wrongdoing if the groom or bride were cheating on the other. If so, it puts “bite your lip” into the realm of time and place, or turns it into an ethical judgment.
There are also incidences where people are told to “bite your lip” for their personal safety and for the safety of others. Such situations occur when there are consequences for revealing such information or opinions. There are many examples across world history where someone did not bite their tongue and gave an honest opinion. Many governments and regimes have punished such people.
In Japan, “bite your lip” falls into the twin ideas of ‘honne’ and ‘tatemae.’ Honne means ‘true feelings’ and is kept internal most of the time. ‘Tatemae’ means public feelings and represents what is appropriate to feel in a social situation. The two feelings are often at loggerheads with one another, but the preservation of social harmony is paramount in their thinking.