Of a person: lacking in restraint; (wildly) unconventional in demeanour or conduct; marked by irresponsible gaiety; violently exuberant, outrageous…

Of undertakings, actions, notions, statements, etc.: Going beyond prudent or reasonable limits; rashly or inconsiderately venturesome; going to…

‘Roving beyond just limits or prescribed methods’ (Johnson); exceeding the bounds of reason or… of dispositions, passions, actions, opinions…

As complement of to be or in other stative expressions (sometimes passing into adjectival use; cf. B.). In a flustered, agitated, or mentally…