Here's a list of 10 common repetitive words that may appear on the SAT, along with examples.

Digital SAT Vocabulary #1

convincing or persuasive. 
Example: The speaker's cogent arguments swayed 
the audience to her side.

a confusing and difficult problem or question. 
Example: The math problem was a conundrum that 
stumped even the best students in the class.

essentially different in kind. 
Example: The two paintings were so disparate in style
that it was hard to believe they were created by the 
same artist.

lasting for a very short time. 
Example: The beauty of the sunset was ephemeral, lasting only a few minutes before fading away.

intended for or likely to be understood by only a small number of people with specialized knowledge or interest. 
Example: The book was filled with esoteric references 
that only a scholar would understand.

treating serious issues with inappropriate humor.  
Example: His facetious comments during the meeting 
were not appreciated by his colleagues.

impossible to understand or interpret. 
Example: The expression on her face was inscrutable, making it hard to tell what she was thinking.

generous or forgiving, especially toward a rival or less powerful person. 
Example: Despite losing the game, the captain of the losing team was magnanimous in his praise of the winning team.

stubbornly refusing to change one's opinion or course of action. 
Example: The politician was obdurate in his refusal to compromise on the issue.

having a harmful effect, especially in a gradual or subtle way. Example: The pernicious effects of air pollution on our health are well-documented.