-ory2 Also -atory, -sory, -tory.
Relating to or involving an action.
[Latin -orius, Latin -orius, sometimes via Anglo-Norman French -ori(e).]
Examples are primarily adjectives. They often contain at, s, or t before the ending, derived from the stem of Latin precursor words. Some examples are compulsory, defamatory, mandatory, obligatory, preparatory, and sensory. They can sometimes also be nouns: accessory, purgatory. One that is now always a noun is directory.