Final answer:
The best synonym for treacherous is dangerous.
Step-by-step explanation:
The best synonym for treacherous is dangerous. While tremendous means very large or great in amount or intensity, it does not convey the negative connotation of betrayal or deception associated with treacherous. Similarly, smooth and straight do not capture the treacherous nature. On the other hand, dangerous implies a risk of harm or injury, which aligns with the meaning of treacherous.
Learn more about Synonyms for treacherous