General opposites:
* Unfamiliar: This is the most direct opposite, meaning not known or recognized.
* Strange: This implies something that is unusual or unexpected.
* New: This refers to something that is fresh and not previously encountered.
* Foreign: This suggests something from a different place or culture.
More specific opposites:
* Alien: This implies something that is completely different and unknown.
* Exotic: This suggests something that is unusual and exciting.
* Uncommon: This refers to something that is rare or not often seen.
* Remote: This suggests something that is far away or difficult to reach.
The best opposite word depends on the specific meaning of "familiar" in the context. For example, if you are talking about a familiar face, the opposite might be "unrecognizable."
Think about the specific situation to determine the most appropriate opposite word.