The term 'dress nattily' can be summarized by the crossword solution 'PREEN, ' which is a five-letter word. To dress nattily means to dress in a neat and stylish manner, often with attention to detail. Preening is the act of grooming oneself, such as adjusting clothing or tidying up one's hair. Therefore, to dress nattily is to take care in one's appearance and present oneself in a neat and attractive way.