dressed to kill

Fig. dressed in fancy or stylish clothes. (See also dressed (up) fit to kill.) Wow, look at Sally! She's really dressed to kill. A person doesn't go on vacation dressed to kill. When Joe came to pick Mary up for the movie, he was dressed up fit to kill and carrying a dozen roses.

wearing clothes that are intended to make people notice you The crowd was young, hip, and dressed to kill.

Also, dressed to the nines. Elaborately attired, as in For the opening of the restaurant she was dressed to kill, or At the opera everyone was dressed to the nines. The first of these hyperbolic expressions dates from the early 1800s and uses kill in the sense of "to a great or impressive degree." The phrase to the nines in the sense of "superlative" dates from the late 1700s and its original meaning has been lost, but the most likely theory is that it alludes to the fact that nine, the highest single-digit numeral, stands for "best." Also see gussied up.