Eye chart number). The denominator indicates the distance in feet at which a person with normal vision could stand to correctly identify the same symbols identified by the person tested. For example, a visual acuity of 20/20 is considered normal. Numerous types of eye charts exist and are used in various situations. For example, the Snellen chart is designed for use at 6 meters or 20 feet, and is thus appropriate for testing distance vision. There is often also a need to test a subject's vision at near or occupational tasks (such as reading or computer use). For these situations, a Rosenbaum
Four-letter word Four-letter word The phrase four-letter word refers to a set of English-language words written with four letters which are considered profane, including common popular or slang terms for excretory functions, sexual activity and genitalia, terms relating to Hell or damnation when used outside of religious contexts or slurs. The "four-letter" claim refers to the fact that a large number of (but not all) English "swear words" are incidentally four-character monosyllables. This description came into use during the first half of the twentieth century. Common four-letter words (in this sense) that are widely considered vulgar or offensive to a notable degree