Difficult to understand; recondite. See Synonyms at ambiguous.(adjective)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "abstruse" in a sentence
"Very enthusiastic, I remember they said you were, on certain abstruse points in comparative philology."
"Greek, and Hebrew languages, and perfectly well knew not only the sciences called abstruse, but those arts which come under the denomination of polite literature."
"Madam, all minds are not gifted with the necessary qualities which the delicacy of those fine sciences called abstruse require."