a.

1. 不熟悉的；不常见的；陌生的[（+to）]
   I saw an unfamiliar face at the door.

   我在门口看到一张不熟悉的面孔。

2. 不熟知的；不通晓的；未见过的[F][（+with）]
   I am unfamiliar with the streets in this neighborhood.

   我不熟悉这一地段的街道。

adj.

1. not known or recognized.
   ▸uncharacteristic.
2. (unfamiliar with) not having knowledge or experience of.