unobtainable

Từ điển WordNet v3.1 - WordNet Dictionary

adjective

not capable of being obtained (Freq. 2)
- a rare work, today almost inaccessible
- timber is virtually unobtainable in the islands
- untouchable resources buried deep within the earth
• Syn:
inaccessible, unprocurable, untouchable
• Similar to:
unavailable
• Derivationally related forms:
inaccessibility (for: inaccessible)