1. In boxing, two quick hits to one's opponent in rapid succession. The boxer's one-two punch was feared by his opponents in the ring.

2. Two negative events that happen at the same time or in rapid succession. My electricity being shut off the same day I lost my job was a terrible one-two punch.

1. Two quick punches delivered to one's opponent in rapid succession, one coming from each hand. The boxer's put his opponent in a daze with a flurry of punches, then brought him down to the mat with the old one-two. The guy refused to leave us alone, so I gave him the old one-two and shut him up for good.

2. Two actions, events, strategies, people, etc., that work in combination to deliver a very effective or powerful result. The two lawyers have become the one-two punch of the firm, bringing a perfect combination of abilities to tackle any case. The storm is predicted to bring the old-one two—devastating winds and a deluge of rainfall.