noun /əˈsʌmp.ʃən/
a) The act of assuming, or taking to or upon ones self; the act of taking up or adopting.
His assumption of secretarial duties was timely.
b) 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.
See Also: assume, assumptive
Wikipedia foundation.