Q: unbeknownst to you とはどういう意味ですか?
A: 気づいていない

Unbeknownst to the students, the teacher had snuck into the room.
Q: unbeknownst to us とはどういう意味ですか?
A: It means that you were not aware of something happening. It's used more so in literature than in spoken language. Examples:
- My brother and I went to the supermarket to buy bread but, unbeknownst to us, our dad had already bought some earlier.
- Unbeknownst to the family, a thief had entered their house.
- Unbeknownst to me, my parents had thrown away all my belongings as soon as I moved out.
Q: unbeknownst とはどういう意味ですか?
A: without (a certain person) knowing
Unbeknownst to me, she bought a car. = without my knowledge, she bought a car (I didn't know)
Q: unbeknownst とはどういう意味ですか?
A: It means without the knowledge of (subject in sentence)

Unbeknownst to me, she submitted the paperwork.(Without me knowing, she submitted the paperwork.)

He continued the race unbeknownst to her. (He continued the race without her knowledge of it.)


Q: unbeknownst は 英語 (アメリカ) で何と言いますか?
A: QAの全文をご確認ください