mysterious
/mi-ˈstir-ē-əs/
adjective
of, relating to, or constituting mystery
exciting wonder, curiosity, or surprise while baffling efforts to comprehend or identify : mystifying
stirred by or attracted to the inexplicable
the mysterious ways of God
heard a mysterious noise
idiom
to talk or behave in a way that makes other people feel that one must have a secret
What are you being so mysterious about?