Containing, expressing, or having the character of a command; mandatory or authoritative in tone.
From command plus the suffix -atory 'relating to or tending to.' Similar to 'mandatory,' it describes something that commands or demands compliance.
The suffix -atory is one of English's 'flavor markers'—when you add it to verbs, it creates adjectives that sound authoritative and formal. 'Commandatory,' 'migratory,' and 'laudatory' all have this official, somewhat archaic tone because they were used in legal and religious documents.
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