Unfamiliar With: Standard Pattern
Unfamiliar With: Standard Pattern records the directly documented construction and keeps guidance bounded to the evidenced complement pattern rather than inventing a broader prohibition.
Use “be unfamiliar with” when a person lacks knowledge or experience of a subject, system, term, or activity.
Key details
Choose the right form
| Context | Use | Decision |
|---|---|---|
| person lacks knowledge/experience of a subject | unfamiliar with | Use “with” to connect the person to the subject, system, term, or activity. |
| thing is not known to a person | unfamiliar to | Use “to” for the different perspective in which the thing is unfamiliar to someone. |
| other uses | check the relation | Do not turn one attested complement into a universal rule. |
Quick tests
Perspective test
Are you describing a person who lacks familiarity with something?
If yes: Use “be unfamiliar with + subject/thing/activity.”
If no: If the thing itself is not known to a person, “unfamiliar to + person” may fit better.
Caveat: The reviewed evidence supports both perspectives; “with” does not replace every other complement.
Examples
I was unfamiliar with the new booking system.
The person lacks knowledge or experience of the system.
Many readers are unfamiliar with the technical term.
“With” links the people to the term they do not know.
The procedure was unfamiliar to the new staff.
This reverses the perspective: the procedure is the unfamiliar thing.
Further guidance
Construction
Use “be unfamiliar with” when a person lacks knowledge or experience of a subject, system, term, or activity.
Style Boundary
Cambridge also uses “unfamiliar to” when something is not known to a person; the two complements can express different perspectives rather than simple interchangeability.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
- UNFAMILIAR | English meaning - Cambridge Dictionary (opens in a new tab)Cambridge University Press & Assessment · Cambridge dictionary evidence for be unfamiliar with something and its meaning boundary.