noun

1. The act of assuming, or taking to or upon oneself; the act of taking up or adopting.

   “His assumption of secretarial duties was timely.”

2. The act of taking for granted, or supposing a thing without proof; a supposition; an unwarrantable claim.

   “Their assumption of his guilt disqualified them from jury duty.”

3. The thing supposed; a postulate, or proposition assumed; a supposition.