adjective

1. 1. intended for or understood by only a chosen few, as an inner group of disciples or initiates: said of ideas, literature, etc.
   2. beyond the understanding or knowledge of most people; abstruse
2. confidential; private; withheld an esoteric plan

Etymology: Gr esōterikos < esōteros, inner, compar. of esō, within < es, eis, into