My understanding of the term ‘dress watch’ refers to mechanical strap watches either manual or automatic wound which tend to be worn with long shirt sleeves and often a jacket. Dress watches primarily have more refined features and in most cases thinner movements than their sporting counterparts.

Design… Classically, dress watches are considered to be watches that you would wear with something more formal, especially a tuxedo. … A two-handed, time-only watch on a legible white dial with only the company marquee and the hour track printed onto it is perhaps the ultimate expression of a true dress watch.

Classic dress watches are known to be small, and whilst these will look great with a suit, they will look a bit off with too casual attire. But as long as you have that in mind and opt for a dress watch that is slightly larger, it can look casual enough to be worn on casual occasions.

A dress watch is supposed to be elegant and modest. A watch that is minimalistic and adds a touch of style, flair, and sophistication, regardless of whether it is worn with formal, semi-formal, or casual attire, is a dress watch.

Characteristics of a Dress Watch:
A Slim Profile – As opposed to their sport model cousins, a dress watch typically has a slimmer profile. …
Smaller or Average Case Size – Most dress watches fall in a 34mm to 40mm case size.
Leather Strap – Dress watches are typically outfitted with a leather strap.