Assumption, n.
Etymology: [OE. assumpcioun a taking up into heaven, L. assumptio a taking, fr. assumere: cf. F. assomption. See Assume.]
1. The act of assuming, or taking to or upon one's self; the act of taking up or adopting. The assumption of authority. Whewell.
2. The act of taking for granted, or supposing a thing without proof; supposition; unwarrantable claim. This gives no sanction to the unwarrantable assumption that the soul sleeps from the period of death to the resurrection of the body. Thodey. That calm assumption of the virtues. W. Black.
3. The thing supposed; a postulate, or proposition assumed; a supposition. Hold! says the Stoic; your assumption's wrong. Dryden.
4. (Logic)
3 more senses
The minor or second proposition in a categorical syllogism.
5. The taking of a person up into heaven. Hence: (Rom. Cath. & Greek Churches)
A festival in honor of the ascent of the Virgin Mary into heaven.
Shades of meaning
Fernald has no entry of its own for assumption; he lists it under assurance, pretense, pride.
Where he writes about it:
Assumption quietly takes for granted superiority and privilege which others would be slow to concede. — from pride