1.
If something or someone is ~, they have not yet been tried out or have not yet experienced a particular situation, so you do not know what they will be like.
The Egyptian Army remained an ~ force...
= untried
ADJ
2.
If you describe something such as a drug or chemical as ~, you mean that it has not been subject to scientific tests to find out if it is safe to use.
...the dangers of giving ~ drugs to people.
ADJ: usu ADJ n