/pri zump"sheuhn/ , n.
1. the act of presuming.
2. assumption of something as true.
3. belief on reasonable grounds or probable evidence.
4. something that is presumed; an assumption.
5. a ground or reason for presuming or believing.
6. Law. an inference required or permitted by law as to the existence of one fact from proof of the existence of other facts.
7. an assumption, often not fully established, that is taken for granted in some piece of reasoning.
8. unwarrantable, unbecoming, or impertinent boldness.
[ 1175-1225; ME: effrontery, supposition praesumption- (s. of praesumptio ) anticipation, supposition, LL: presumptuousness, equiv. to praesumpt ( us ) (ptp. of praesumere to undertake beforehand; see PRESUME) + -ion- -ION ]
Syn. 8. audacity, effrontery, arrogance, gall.