Like many people, I find theoretical physics baffling.
inexplicable formal impossible to explain
For some inexplicable reason her mind went completely blank.
Some things in life are inexplicable.
enigmatic formal mysterious and difficult to understand, but also often attractive or interesting – used especially about people, their expressions, or things they say
She gave him an enigmatic smile.
an enigmatic remark
cryptic formal having a meaning that is difficult to understand, and is not expressed in a cleardirect way – used especially about things that people say or write
I got a rather cryptic message from him.
cryptic comments
be a mystery if something is a mystery, you cannot understand how or why it happens
Four years later, his death remains a complete mystery.
It’s all a mystery to me.
be shrouded/veiled in mystery if an event or a situation, especially one that happened a long time ago, is shrouded in mystery, it is mysterious because no one knows exactly what happened
Stone age civilization, veiled in mystery as it is, has provided the greatest challenge to historians.
in mysterious circumstances• Eight others connected directly or indirectly with the dig later diedin mysterious circumstances.• The defendantsstored on their land large quantities of combustiblematerials which ignitedin mysterious circumstances.• Some one has been murdered in mysterious circumstances: how has it come about?
mysterious about• Nelligan was mysterious about whom she modeled the character on.