To authenticate by means of belief; to surmise; to suppose to be true, especially without proof

“We assume that, as her parents were dentists, she knows quite a bit about dentistry.”

To take on a position, duty or form

“Mr. Jones will assume the position of a lifeguard until a proper replacement is found.”

To adopt a feigned quality or manner; to claim without right; to arrogate

“He assumed an air of indifference”

Used in a manner intended to deceive; pretended; simulated.

Supposed or presumed.