To be presumptuous; with on, upon, to take advantage (of), to take liberties (with).
To take as a premise; to assume for the sake of argument.
With infinitive object: to be so presumptuous as (to do something) without proper authority or permission.
To assume or suggest to be true (without proof); to take for granted, to suppose.
To be courageous; to regain one's courage.
Used when encouraging someone to bear or take up a difficult situation.