Of a person: that has given careful thought to something; disposed or inclined to consider matters carefully; judicious, deliberate; prudent…

Filled or laid with ballast; made steady or stable.

‘Equipoised, steady’ (Schmidt). Obsolete.

Of judgement, opinion, etc.: Considered, balanced. †Of a person: Having a balanced and steady judgement. Cf. well-weighed, adj.

That does not deviate; not perverse.

Not muddied (literal and in extended use).

Of judgement, etc.: Of a sober, sound, or practical character.

Of the judgement: Keen, acute.

(un-, prefix1 affix 1.)