The only "dress code" onboard the Disney ships is "no swimwear or tank tops for dinner". Beyond that, you'll see all manner of dress for dinner. From fancy to shorts (and not "dress" shorts - don't really think there is such a thing IMO, sorry).
My husband wore dress pants & my sons & nephew wore golf shorts. We call them dress shorts where I live too.
All wore button down shirts.
The ladies wore sundresses.
You will see all kinds of clothing in the MDRs.
We did a 4 night in dream and 60% of the people were super casual. T-shirts, cargo style shorts and flip flops. Most kids were in character tees and comfy shorts. 35% were in sundresses and collared shirts and nice khakis and the other 5% were a little dressier (cocktail dresses and dress pants and dress shirt) and honestly looked out of place. Go with what your comfortable in. I stressed over packing nice clothes and then when I saw everyone else was wearing I was mad I stressed about it!
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