A sentence with a synonym context clue contains?

A sentence with a synonym context clue contains two words that mean the same thing. One of these words will be unfamiliar, and the other will be a familiar synonym, helping you understand the meaning of the unfamiliar word.

Example:

The serene lake was so calm and peaceful that it felt like a different world.

In this sentence, "serene" is the unfamiliar word. "Calm and peaceful" are synonyms for "serene," giving us a clear idea of its meaning.