Strictly speaking a wat is a Buddhist sacred precinct with a vihara (quarters for bhikkhus), a temple, an edifice housing a large image of Buddha and a structure for lessons. A site without a minimum of three resident bhikkhus cannot correctly be described as a wat although the term is frequently used more loosely, even for ruins of ancient temples. As a transitive or intransitive verb, wat means to measure, to take measurements; compare templum, from which temple derives, having the same root as template.
In everyday language in Thailand, a wat is any place of worship except a mosque (Thai สุเหร่า surao or มัสยิด masjid; a mosque may also be described as โบสถ์ของอิสลาม - bot khong itsalam, literally "Islam church") or a synagogue (Thai สุเหร่ายิว - surao yiw). Thus a wat chin is a Chinese temple (either Buddhist or Taoist), wat khaek is a Hindu temple and wat khrit or wat farang is a Christian church, though Thai โบสถ์ (โบสถ์ bot) may be used descriptively as with mosques.
In Cambodia, a wat is used to refer to all kinds of places of worship. Technically, wat generally refers to a Buddhist place of worship, but the technical term is វត្តពុទ្ធសាសនា wat putthasasana. A Christian church can be referred as វិហារយេស៊ូ vihear Yesaou or "Jesus vihear". Angkor Wat អង្គរវត្ត means "city of temples".
According to Thai law, Thai Buddhist temples are of two types:
- Wat (วัด; wat) are temples which are have been endorsed by the state and have been granted wisungkhamasima (วิสุงคามสีมา), or the land for establishing central hall, by the king. These temples are divided into:
- Samnak song (สำนักสงฆ์; samnak song) are temples without state endorsement and wisungkhamasima.
A typical Buddhist wat consists of the following buildings:
- chaidei or chedi (Khmer ចេតិយ), (Thai เจดีย์) (from Sanskrit: chaitya, temple) - usually conical or bell-shaped buildings, often containing relics of Buddha
- vihear (Khmer វិហារ),wihan (Thai วิหาร) from Sanskrit: vihara) - a meeting and prayer room
- mondop (Thai มณฑป) (from Sanskrit: Mandapa) - a usually open, square building with four arches and a pyramidal roof, used to worship religious texts or objects
- sala (Khmer សាលា), (Thai ศาลา) (from Sanskrit: Shala - School, from an earlier meaning of shelter) - a pavilion for relaxation or miscellaneous activities
- bot โบสถ์ or ubosoth อุโบสถ์ (from Pali uposatha) - the holiest prayer room, also called the "ordination hall" as it is where new monks take their vows. Architecturally it is similar to the vihara; the main differences are the eight cornerstones placed around the bot to ward off evil. The bot is usually more decorated than the viharn.
- bibiloteca (Thai หอไตร) - Tripitaka library where Buddhist scriptures are kept
- drum tower (Thai หอกลอง)
- bell tower (Thai หอระฆัง)
- multipurpose hall (Thai: ศาลาการเปรียญ, study hall) is a building in a wat. 
The living quarters of the monks, including the กุฏิ (pronounced kut, kutti or kuti - monk cells) are separated from the sacred buildings.
The roofs of Thai temples are often adorned with chofahs.
|Look up wat in Wiktionary, the free dictionary.|
Some well-known wats include:
- Angkor Wat, Siem Reap
- Wat Preah Keo, Phnom Penh
- Wat Botum Vathey, Phnom Penh
- Wat Moha Montrey, Phnom Penh
- Wat Ounalaom, Phnom Penh
- Wat Phnom, Phnom Penh
- Wat Bakan, Pursat
- Lanna (Northern Thailand)
- ราชกิจจานุเบกษา, ประกาศกระทรวงธรรมการ แผนกกรมสังฆการี เรื่อง จัดระเบียบพระอารามหลวง, เล่ม ๓๒, ตอน ๐ ก, ๓ ตุลาคม พ.ศ.๒๔๕๘, หน้า ๒๘๔
- Pura, Balinese temples
- Candi, temples of ancient Indonesia, especially Java
- Kyaung, Burmese monastery