esoteric

adj

1. Intended for or likely to be understood by only a small number of people with a specialized knowledge or interest, or an enlightened inner circle.

   “The writing in this manual is very esoteric; I’d need a degree in engineering just to understand it!”

   “In this situation Hitler availed himself of a time-honored device-the use of esoteric language. In all periods of history, when government or society has put limits on public discussion, those who wish to circumvent censorship resort to the use of esoteric language. Exoterically understood, the text is unexceptionable, but to the insiders who know how to interpret the words, the message is revolutionary and dangerous to the status quo.”

2. Having to do with concepts that are highly theoretical and without obvious practical application; often with mystical or religious connotations.

   “When he spoke to me of esoteric mysteries I wanted to say to him,"Don't give me that spiritual hokum, friend!"”

3. Confidential; private.

   “an esoteric purpose”

   “an esoteric meeting”

noun

1. An esoteric doctrine or treatise; esoteric philosophy.
2. One who believes, or is an initiate, in esoteric doctrines or rites.