In the human body, the midriff is the section of the body between the chest and the waist, i.e. the diaphragm area. Its main outside anatomical feature is the navel. "Midriff" is often misspelled "mid-drift" or "midrift".
It is a word of very old origin in the English language, known before 1000 AD. It is written in Middle English as "mydryf". In Old English it is written as "midhrif", with the old word "hrif" literally meaning stomach. The word was essentially obsolete after the 18th century, but the word was revived in 1941 in the world of fashion. This was partly to avoid use of the word "belly" which many women consider undesirable in reference to their bodies as it has connotations of obesity.
In some cultures, exposure of the midriff is socially discouraged or even banned. In Western cultures and others, especially during the late 1990s, it became fashionable for women to expose the midriff. For a period during the early 1980s, bare midriffs were in style for men, with several manufacturers producing t-shirts that ended above the navel, mainly for athletic purposes. However, in recent years shirts exposing the male midriff are associated with homosexuality and effemininity.
In Beijing, where the hot weather can be harsh, men commonly roll up their shirts, exposing their midriff and navel. This is done purely to relieve themselves of the heat, as it is frowned upon for them to completely remove their shirts. However, women in Beijing usually do not do this.
According to PBS Frontline documentary, "The Merchants of Cool", Midriff is a marketing classification for an American, teenage female characterized as prematurely adult, consumed by appearances, and a collection of the same old sexual cliches.
Nowadays, the midriff is commonly revealed when girls wear tighter clothing that hugs the skin. That is, in ordinary standing positions, the midriff may not be visible, but during stretching or other actions that require the arms to be raised, the midriff and navel is commonly visible. Most American secondary schools have a rule against attire that leaves the midriff exposed. Some schools will require the student to raise her arms if it is suspected that her shirt will expose her midriff.
In the Sherman High School dress code, it is quoted that "there must be no exposure of the midriff area or undergarments. The midriff area must not be seen while bending over, while standing, raising arms, and stretching." This particular school district is not the only one that enforces this code.
In most schools the midriff must be covered at all times except when stretching.