Triad

A triad, a group of three, may refer to:

• Triad (Greek philosophy), Pythagorean symbol for the number three
• Triad (music), set of three notes, most commonly forming a diatonic tertian chord
• Triad (relationship), term for a relationship between three people
• Triad (religious) three deities commonly associated together; three deities forming a group with common associations; three deities thought of as three phases of one deity; or three entities thought of as aspects of one deity (e.g. the "great goddess" or Triple Goddess - grandmother, mother, and daughter or, crone, matron, and maiden, and in Catholicism - father, son, spirit); triple deities
• Triad (sociology), term for a group of three people as a unit of study
• Triad (underground societies), a term that describes many branches of Chinese underground society and/or organizations
• Welsh Triads, collections of Medieval Welsh legend and history
• Triplism frequently occurring in religion and mythology

Medicine

In medicine, a triad often refers to three symptoms of a syndrome, such as the following.

• Triad (anatomy), structure in skeletal muscles, formed by a T tubule surrounded by sarcoplasmic reticulum
• Catalytic triad, biochemical term for three amino acid residues found within some proteases
• Beck's triad (cardiology), three typical symptoms of cardiac tamponade
• Beck's cognitive triad, three types of negative thought present in depression
• Charcot's triad, either of two sets of clinical signs, relating to multiple sclerosis or ascending cholangitis
• Cushing's triad, a set of three signs showed by patients with head injuries
• Dieulafoy's triad, a classic sign of acute appendicitis
• Female athlete triad, three symptoms of low energy availability in female athletes
• Hutchinson's triad, a common pattern of presentation for congenital syphilis
• Meckler's triad, used to diagnose Boerhaave syndrome
• Virchow's triad, a set of three signs attributed to Rudolf Virchow describing the pathogenesis of venous thrombosis
• Whipple's triad, a set of three conditions proving hypoglycemia as the cause of a person's symptoms
• MacDonald triad, three childhood traits that are associated with anti-social personality disorder

Organizations, brands, and products

• Triad (environmental science), management system for environmental cleanup
• Triad (underground societies), Chinese organized crime groups
• Triad Demand, UK electrical power demand measurement

Placenames

• The Piedmont Triad, North Carolina, USA region

Computing

• Triad (computers), group of three phosphor dots used in some computer monitors
• Triad C64, Commodore 64 cracking group
• Rise of the Triad, computer game
• TriadCity, a MUD with strong literary themes

Popular culture

• Triad (Battlestar Galactica), fictional ball sport
• The Triad (Charmed), fictional group of three powerful demons
• Triiad, a fictional alien species from the television series Hypernauts
• Triad (superhero), alias of fictional DC Comics super hero Triplicate Girl
• Triad, a 1967 song by David Crosby, with versions recorded by Jefferson Airplane on Crown of Creation, by Crosby, Stills Nash & Young on Four Way Street, and by the Byrds on The Notorious Byrd Brothers
• Triad (album), a 1976 album by Spontaneous Combustion.
• Triad, a song by Tool from their 2001 album Lateralus
• The Hong Kong Triad, a song by Thievery Corporation from their 2000 album The Mirror Conspiracy

See also

National Grid (UK): Triad demand