1. Morally or legally constraining or binding
   "attendance is obligatory"; "an obligatory contribution"
   - irremissible 
2. Required by obligation or compulsion or convention
   "he made all the obligatory apologies"

See also: bounden [archaic], compulsory, de rigueur, imposed, incumbent on, indispensable, mandatory, necessary, obligatorily, prerequisite, required

Antonym: optional

Encyclopedia: Obligatory

• Gulf of St. Lawrence
• Gulf of Suez
• Gulf of Tehuantepec
• Gulf of Thailand
• Gulf of Venice
• Gulf States
• Gulf stream
• Gulf War
• Gulf War syndrome
• gulfweed
• gull
• Gullah
• gullet
• gulley
• gullibility
• gullible
• Gulliver
• gully
• gullywasher
• Gulo
• Gulo gulo
• Gulo luscus
• gulosity
• gulp
• gulper