Something that is unknown to someone or something happening without someone's knowledge.
Examples:
She went to the party unbeknown to her parents.There was a surprise waiting, unbeknown to the guests.Unbeknown to us, the plan was already in action.
Synonyms:
Antonyms:
Unbeknownst
Not known or unnoticed by someone
Examples:
Unbeknownst to him, they planned a surprise party.She slipped away, unbeknownst to the bustling crowd.Unbeknownst to many, the artist lived in seclusion.
Synonyms:
Antonyms:
Ways to tell them apart:
Both words mean without the knowledge of someone and are often followed by to.
Unbeknownst is more commonly used in modern English than unbeknown, especially in American English.
Some grammar purists might argue unbeknown is the more correct form, as it is the older usage.
Unbeknownst contains an additional st' at the end, which might be easier to use in informal settings, adding a soft tone to the word.
Remember, both are perfectly acceptable to use, but context and audience could inform which one might be more appropriate.