Adrenergic stimulation is an activity in the body which is characterised by epinephrine release in the blood or the norepinephrine release occurring within the sympathetic nerve endings. This so-called body activity could have two effects: it could either enhance the body, or inhibit it from performing a certain task/performing in its normal state. The stimulation involves contraction or dilation of some of the muscles in the body (e.g. the heart, and other smooth muscles having surrounded by the most blood vessels including the iris).
This is a good example of both an enhancement or inhibitory reaction: When the contraction of the smooth muscles is inhibited, Adrenergic chemicals are released (e.g. bronchioles), causing it to dilate.