1.
If you say that something is ~, you mean that it is likely to be true or likely to happen.
It is ~ that the medication will suppress the symptom without treating the condition...
An airline official said a bomb was the incident’s most ~ cause.
= likely
? unlikely
ADJ: oft it v-link ADJ that vagueness
2.
You can use ~ to describe a role or function that someone or something is likely to have.
The Socialists united behind their ~ presidential candidate, Michel Rocard.
= likely
ADJ: ADJ n