名詞 unknown:

1. an unknown and unexplored region
   同義詞：unknown region, terra incognita
2. anyone who does not belong in the environment in which they are found
   同義詞：stranger, alien
3. a variable whose values are solutions of an equation
   同義詞：unknown quantity

形容詞 unknown:

1. not known
2. being or having an unknown or unnamed source
   同義詞：nameless, unidentified, unnamed
3. not known to exist- Edith Wharton
4. not famous or acclaimed
   同義詞：obscure, unsung
5. not known before
   同義詞：strange

1. The new sales director is still a bit of an unknown quantity.
   新來的銷售部主任大家還不大了解。
2. He was an unknown painter one year ago.
   一年前，他還是一個不為人知的畫家。
3. The director cast her in a leading part when she was a young unknown of 16.
   當她還是一個十六歲的無名少女時，導演選中她演主角。