From Longman Dictionary of Contemporary Englishobligatoryob‧lig‧a‧to‧ry /əˈblɪɡətəri $ -tɔːri/ ●○○ adjective 1 formalMUST something that is obligatory must be done because of a law, rule etc SYN compulsory, mandatoryit is obligatory for somebody (to do something) It is obligatory for companies to provide details of their industrial processes.► see thesaurus at necessary2 ALWAYS/EVERY TIME[only before noun] used humorously to describe something that is always done or included in a particular situation She offered him the obligatory cup of tea.
Examples from the Corpus
obligatory• By the time I had done the obligatory 20-minute brushwork on Vaquero, my arms ached.• Evening dress is usual, but not obligatory.• Appreciation of this reality begins with the popular, indeed obligatory, definition of work.• It is now obligatory for all competitors to wear face protectors.• Military service is obligatory for all men between 18 and 27.• Voting is obligatory for Brazilians aged 18 to 69.• For their part the priests declared that without such obligatory gifts they would not be able to survive.• They sent out the obligatory memo both before and after the project.• In front is a lush, densely landscaped yard; in back is the obligatory pool.• Award-winning magician Oscar Mu oz also pulls the obligatory rabbit out of the hat, and even produces a bird or two.• The truth is that obligatory recycling protects markets as well as the environment.• The obligatory standing ovation when he first entered the game against the Golden State Warriors lasted less than a minute.From Longman Business Dictionaryobligatoryo‧blig‧a‧to‧ry /əˈblɪgətəri-tɔːri/ adjective formalLAW something that is obligatory must be done because of a law, rule etcSYNCOMPULSORY, MANDATORYThe Housing and Town Planning Act made it obligatory for local authorities to prepare surveys of their housing needs. 