Catecholaminergic means "related to catecholamines". The catecholamine neurotransmitters include dopamine, epinephrine (adrenaline), and norepinephrine (noradrenaline).
A catecholaminergic agent (or drug) is a chemical which functions to directly modulate the catecholamine systems in the body or brain. Examples include adrenergics and dopaminergics.