1. Presumed to be true or real without conclusive evidence.
2. Intended: medication that is supposed to relieve pain.
3. 1. Required: He is supposed to go to the store.
   2. Permitted: We are not supposed to smoke here.
   3. Firmly believed; expected: You're supposed to be my friend.

SYNONYMS   supposed, conjectural, hypothetical, putative, reputed, suppositious, supposititious. These adjectives mean put forth or accepted as being true on inconclusive grounds: the supposed cause of inflation; conjectural criticism; the hypothetical site of a lost culture; a foundling's putative father; the reputed author of the article; suppositious reconstructions of dead languages; supposititious hypotheses.
ANTONYM  certain

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.