Presumption, n.
Etymology: [L. praesumptio: cf. F. présomption, OF. also presumpcion. See Presume.]
1. The act of presuming, or believing upon probable evidence; the act of assuming or taking for granted; belief upon incomplete proof.
2. Ground for presuming; evidence probable, but not conclusive; strong probability; reasonable supposition; as, the presumption is that an event has taken place.
3. That which is presumed or assumed; that which is supposed or believed to be real or true, on evidence that is probable but not conclusive. "In contradiction to these very plausible presumptions." De Quincey.
4. The act of venturing beyond due beyond due bounds; an overstepping of the bounds of reverence, respect, or courtesy; forward, overconfident, or arrogant opinion or conduct; presumptuousness; arrogance; effrontery. Thy son I killed for his presumption. Shak. I had the presumption to dedicate to you a very unfinished piece. Dryden. Conclusive presumption. See under Conclusive. -- Presumption of fact (Law), an argument of a fact from a fact; an inference as to the existence of one fact not certainly known, from the existence of some other fact known or proved, founded on a previous experience of their connection; supposition of the truth or real existence of something, without direct or positive proof of the fact, but grounded on circumstantial or probable evidence which entitles it to belief. Burrill. Best. Wharton. -- Presumption of law (Law), a postulate applied in advance to all cases of a particular class; e. g., the presumption of innocence and of regularity of records. Such a presumption is rebuttable or irrebuttable.
Shades of meaning
Fernald has no entry of its own for presumption; he lists it under assurance, impudence, prejudice, pride, temerity.
Where he writes about it:
A presumption (literally, a taking beforehand) is a partial decision formed in advance of argument or evidence, usually grounded on some general principle, and always held subject to revision upon fuller information. — from prejudice
There is always a presumption in favor of what exists, so that the burden of proof is upon one who advocates a change. — from prejudice
Presumption claims place or privilege above one's right; pride deems nothing too high. — from pride
In the presence of superiors overweening pride manifests itself in presumption or insolence; in the presence of inferiors, or those supposed to be inferior, pride manifests itself by arrogance, disdain, haughtiness, superciliousness, or in either case often by cold reserve. (See RESERVE under modesty.) Pride is too self-satisfied to care for praise; vanity intensely craves admiration and applause. — from pride
We say it is amazing that one should have had the temerity to make a statement which could be readily proved a falsehood, or to make an unworthy proposal to one sure to resent it; in such use temerity is often closely allied to hardihood, audacity, or presumption. — from temerity