The historical reference was too obscure for most of the audience to understand.
Synonyms for obscure
unclear
vague
dim
Antonyms for obscure
clear
obvious
well-known
Practice obscure on real SAT questions
Vocabulary like obscure appears on the Digital SAT in Words-in-Context questions, where you choose the word that fits a passage's meaning and tone. You can also drill this word with vocabulary flashcards.