Seems like the word frumpy exists to shame women who, as per the dictionary definition mentioned earlier in the thread, do not keep up with fashion or make themselves sufficiently attractive (to the male gaze).
What's awful is that the quoted post makes it clear that just by virtue of ageing, gaining weight & having less time & money, women are told they're inadequate.
(Younger women are also told they're inadequate regardless of their looks because it's essentially about putting women down in order to control them.)
I mean, how dare women present themselves in public whilst their anatomy & physiology follows the typical lifespan pattern for their sex. Not sexy because you'd rather be warm, get back inside where you can do all the unpaid domestic & caring work.
Fashion, style & beauty require time & money.
And if you're interested in fashion, visual art & design principles applied to clothes? Superficial & high maintenance. That money could've been spent better, you're so selfish.
Femininity is both compulsory (enforced by legal, social & economic consequences) & devalued because of misogyny.
And yes, I dress well & I'm rewarded for my compliance / social conformity. But I can still see that it's harmful to women & not empowering to 'meet' beauty standards.