Definition of unbeknownst
- unknown to someone
Usage examples of unbeknownst
Unbeknownst to her, the team had planned a surprise celebration while she was out of the office.
The old pipe had been leaking for weeks, unbeknownst to the homeowners until a water stain appeared on the ceiling.
Unbeknownst to the students, the teacher had already posted the answers after the exam deadline passed.