- From Middle English -orie, from Latin adjective suffix -tōrius.
- From Latin noun suffix -tōrium 
- of or pertaining to, serving for; adjective suffix appended to various words, often nouns but also verbs, to make an adjective form. Often added to words of Latin origin, but used with other words also
- that which pertains to, or serves for; noun suffix appended to various words
- “-ory” in The American Heritage Dictionary of the English Language, 4th edition, Boston, Mass.: Houghton Mifflin, 2000, →ISBN.
- -ory in Webster’s Revised Unabridged Dictionary, G. & C. Merriam, 1913