In a sentence
Attendance at the safety briefing is obligatory for all new employees.
Synonyms
compulsorymandatoryrequired
Antonyms
optionalvoluntarydiscretionary
Keep going
See all More GRE words starting with O
oaf
a stupid, clumsy, or boorish person
obdurate
stubbornly refusing to change one's mind or course of action
obeisance
a gesture or attitude of deep respect or submission
obeisant
showing deferential respect or submissive obedience
obelisk
a tapering stone pillar with a pyramidal top, typically erected as a monument
obese
grossly overweight to a degree that poses a health risk
obfuscate
to make something deliberately unclear or confusing
obfuscation
the act of making something deliberately unclear or confusing
Learn words the way the GRE tests them.
Vocabulary sticks when you meet it in real sentences. Practise these words inside text completion and sentence equivalence questions.