A supposition is a guess or a hypothesis. Your supposition that your kids will automatically wash their hands before dinner is probably false. You'd best remind them to do it or risk dirty hands at dinner.

What's the difference between an assumption and a supposition — both nouns that are often taken as synonyms for each other? An assumption is an idea or theory that is usually made without proof. A supposition, on the other hand, has the connotation that the idea or theory is testable and provable. If you are to meet someone named Hunter, you may make the assumption that you are meeting a man. But if you know that Hunter lives in an all-female dorm, you may have the supposition that Hunter is a woman.

Definitions of supposition
  1. noun
    the cognitive process of supposing
    synonyms: supposal
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    the act of presupposing; a supposition made prior to having knowledge (as for the purpose of argument)
    type of:
    reasoning that involves the formation of conclusions from incomplete evidence
  2. noun
    a message expressing an opinion based on incomplete evidence
    synonyms: conjecture, guess, hypothesis, speculation, surmisal, surmise
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    successful conjecture by unusual insight or good luck
    type of:
    opinion, view
    a message expressing a belief about something; the expression of a belief that is held with confidence but not substantiated by positive knowledge or proof
  3. noun
    a hypothesis that is taken for granted
    synonyms: assumption, supposal
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    an intuitive assumption
    base, basis, cornerstone, foundation, fundament, groundwork
    the fundamental assumptions from which something is begun or developed or calculated or explained
    given, precondition, presumption
    an assumption that is taken for granted
    basic assumption, constatation, self-evident truth
    an assumption that is basic to an argument
    non sequitur
    (logic) a conclusion that does not follow from the premises
    meat and potatoes
    the fundamental part
    type of:
    hypothesis, possibility, theory
    a tentative insight into the natural world; a concept that is not yet verified but that if true would explain certain facts or phenomena
Word Family

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