Is there a value-neutral term for dressing 'modestly'?

Yes. Some of the women wear long, floor length dresses. I always wear loose pants and a T-shirt or sweater.

With obvious exceptions duly noted, I presume – for example, for employees of a beachside surf shop.

It’s absolutely making a value judgment - to say that one outfit is “appropriate” implies that others exist that are “inappropriate”. You may not be expressing a value judgment about the person wearing the clothing when you call it 'appropriate" - but then neither are you making a judgment about the person when you describe their attire as "modest.
You might be expressing a judgment about the person if you called their clothing “immodest” - but if so, you would also be making a judgment about a person if you described their clothing as “inappropriate”. I think there are certain words that only imply judgment in one direction - even if a person always dresses in exactly the same way, they will almost accidentally be dressed appropriately sometimes in a broken-clock-is-right-twice-a-day-way, so the fact that someone is dressed appropriately today doesn’t really tell you anything about them. And the fact that someone is all covered up today ( perhaps because they are going to a funeral ) doesn’t mean they aren’t on the corner in a G-string the rest of the time.

I don’t agree with that. Saying “modest” means first of all that you have taken note sufficiently to comment. There is a judgment underlying that. What that judgment is depends on the perspective of the speaker.

We see a Muslim woman wearing a dress that covers her from neck to ankles and is wearing a hijab.
“She was dressed modestly.”

An L.A. resident sees her walking down Wilshire Boulevard, and says this to indicate that she was dressed more modestly than what one normally sees. It is an indication that the woman was seen as conservative enough to remark on.

A Saudi member of the religious police sees her walking down Tahlia Street and is pleased that she is dressed according to Islamic tradition. It is an indication that the woman has been evaluated and passes.

If a man were to wear long pants and long-sleeves buttoned up to the top, you could say that he was dressed “warmly,” whereas a man in a tank top and running shorts was dressed “coolly.” This is absolutely not a perfect response, I know. First of all because the texture and thickness of the fabric you wear plays a role in whether or not something is warm, and also because it kind of presumes that the reason you dressed the way you did was in response to the weather or temperature at the office or something. But I do think saying someone dressed warmly implies being covered up without assigning a value judgment to it.

“Modest” is never going to be a value neutral term because nobody, I repeat NOBODY, ever uses the term “modest” to describe a man’s clothing. Because modesty is something only required of women. Since it’s a gendered term with religious connotations, there isn’t a way to get that idea across without a value judgment going along with it. Closest you’re going to get is “business attire.”

“Full coverage” as in “she was wearing an outfit that provided full coverage” works for me, although I don’t have a problem with using “modest” which is what most people who dress that way intentionally use.

You left out half my sentence. It was an if/then type of statement responding to someone who felt “appropriately” did not imply any value judgments. Nope, either “appropriately” and “modest” both imply value judgments or neither does. Because after all, saying “appropriately” means first of all that you have taken note sufficiently to comment and so on.

I think you’re basically right, although I might use the word “immodest” to describe a guy whose ball sack was hanging out the leg of his gym shorts.

Your boss makes you wear clean clothes?

Fascists.

Sure, but nobody would probably call it “modest” either, even if it was a meat burqa and none of her skin was showing.

Modest dress, in my way of thinking, is a subset of conservative dress, in that conservative means not shocking, not revealing, not attention getting. Modest would imply that there’s a certain extra attempt for the clothing to be sexual.

But they go hand-in-hand; a woman in some tight-fitting business suits isn’t going to be conservative or modest. I mean, I can’t think of a situation where women’s clothing could be conservative, yet not modest.

It’s difficult to make the distinction. Take the woman wearing a typical burka. If she was walking on the streets of Tehran nobody would bat an eyelash. The same woman woman wearing the same burka might not be said to be dressed conservatively if she was on the beach somewhere in France. In that setting there might be some people who would say she was trying to be provocative rather than conservative, albeit not in a sexual way.

This discussion begs the question of what clothes are for, after basic physical warmth/shade/freedom from abrasion needs are met.

I wil proffer that clothes are for signaling. In which case any kind of description will contain an assessment, which will contain a judgement.

I was at my local hippie food store today and noticed a guy wearing a gimme cap, greasy hair that was five inches long, baggy cheap pants. This guy had his back to me, he was walking away in the parking lot. In a couple seconds I had made a total judgement about this guy’s education, economic reality, and politics. Then a thin, long-legged woman in her thirties came past with thick, styled, hennaed hair, mascara, black leggings with giant shiny rainboots, and a slim-fitting parka vest, and some kind of high-heeled clog sandals. Ditto, took me a few seconds (I was distracted by those interesting clogs).

If someone’s clothing was described as “modest” I would picture a woman, not a man, with some as-yet unidentified religious belief. Mennonite? Nun? Need more data.

The word presently connotes a belief system. There is no real equivalent.

“Appropriate” doesn’t work, because appropriateness depends on context. A bikini is appropriate attire on the beach, but even on a beach, it’s not “modest”.

Nor is “modesty” just a matter of coverage: A skintight head-to-toe bodysuit would generally not be described as “modest”.

The definition of modest is someone or something that is humble or shy or not extreme.
An example of modest is a person who doesn’t easily take their clothes off around others.
An example of modest is a simple house.

There is denotation. But then there is connotation.

But that’s exactly what has been discussed lately in terms of modest dress: Halima Aden Makes History as the First Model to Wear a Hijab and Burkini in Sports Illustrated Swimsuit

In the late 90’s, I was running a small research group in a large, conservative company. The standard was coat and tie except on “casual Fridays”, when the tie could be forgone. I should note that adherence to this was forgiven in our engineers and scientists as long as coat and tie was worn in meetings with management or customers. Our CEO, persuaded by HR that this was behind the times, put out a webcast to the entire population in which he announced the company was going “casual” all days of the week while (shockingly) wearing a flannel shirt. As part of the announcement, he noted that “appropriate” dress for work situations was still expected.

The next day, I’m walking down a corridor when one of my guys comes walking the other way. He’s wearing: an open lab coat, running shorts, and flip flops. Period.

I felt compelled to have an ad hoc discussion with him on the exact meaning and overlap of the terms “casual” and “appropriate”.

It’s not as much of a skintightbodysuit as it appears in that photo. It might be if it wasn’t for that coat-like piece. But the other burkinis in my link look nothing like bodysuits- the geometric one looks like a dress with leggings/pants under it.

Appropriate: My wife once worked in a company whose owner thought that even in the middle of a Montreal winter, slacks on a woman were always inappropriate. Only a skirt, high heels, and nylons were to him, appropriate. Even though she never met a client. But she wore what she damn pleased and he pretended to ignore it.

On the other hand, as a professor, I always wore whatever I wanted. Usually jeans and a plaid shirt, but on a warm day in the early fall, if I felt that shorts and a T were called for, that’s what I wore.