1. Something that is believed to be true without proof.
2. The action of taking to oneself; reception, adoption.
3. The action of receiving up into heaven; ascent to or reception into heaven; the reception of the Virgin Mary into heaven, with body preserved from corruption, which is a generally accepted doctrine in the Roman Catholic Church.

Also the feast held annually on the 15th of August in honor of this event.

4. The action of taking for or upon oneself.
5. The taking upon oneself of a form or character; the formal taking of an office or a position.
6. In law, a promise or undertaking, either oral or in writing not sealed.
7. The action of laying claim to as a possession, unwarrantable claim, usurpation.
8. A taking too much upon oneself, a laying claim to undue importance; arrogance.
9. The taking of anything for granted as the basis of argument or action.
10. That which is assumed or taken for granted; a supposition, postulate.
11. In logic, the minor premise of a syllogism.

The underlying agreements or statements made in the development of a logical argument, course of action, decision, or judgment that are not explicitly voiced nor necessarily understood by the decision maker or judge.

Some examples of tacit assumptions are those arguments supporting moral, religious, racist, organizational culture, and political arguments.