ESOTERIC

Not widely known

• Abstruse

• Arcane

• Difficult to understand

• Enigmatic

• For initiates only

• Incomprehensible

• Indecipherable

• Inscrutable

• Intended for a select few

• Just for a few

• Known by few

• Known only to insiders

• Like the in-group

• Like trivia

• Limited-appeal

• Mysterious

• Not clear to most

• Not for everyone

• Not for the masses

• Obscure

• Odd, as a range of knowledge

• Only for certain tastes

• Puzzling

• Rarefied

• Recondite

• Secret

• Shrouded in mystery

• Understood by a few

• Understood by a select few

• Way out there

• Way-out