The word adornment is the key word in both verses, and according to English syntax, the subject comes first as opposed to Greek which has very flexible syntax or word order where they would arrange word order according to their choice or purpose of the point of argument. In Timothy, the same word kosmos is used in infinitive form, whereas in Peter, it is a noun. It depends on the translators on how do they want to convey the same in their target language. It doesn't change the meaning if they turn a noun to adjective.
The main meaning of kosmos is adornment, decoration. The space cosmos usage may have been used as the decoration of the heavens with stars. The meaning of both the verses is basically same, they are saying to adorn yourself with spiritual qualities rather than external. They are instructing against physical adornment or makeup and fancy clothing. However, this doesn't mean they are absolutely forbidding any kind of basic adornment and dressing etc.
cosmos (n.)
etymology
c. 1200, "the universe, the world" (but not popular until 1848, when
it was taken as the English equivalent to Humboldt's Kosmos in
translations from German), from Latinized form of Greek kosmos "order,
good order, orderly arrangement," a word with several main senses
rooted in those notions: The verb kosmein meant generally "to dispose,
prepare," but especially "to order and arrange (troops for battle), to
set (an army) in array;" also "to establish (a government or regime);"
"to deck, adorn, equip, dress" (especially of women). Thus kosmos had
an important secondary sense of "ornaments of a woman's dress,
decoration" (compare kosmokomes "dressing the hair," and cosmetic) as
well as "the universe, the world."
Pythagoras is said to have been the first to apply this word to "the
universe," perhaps originally meaning "the starry firmament," but it
later was extended to the whole physical world, including the earth.
For specific reference to "the world of people," the classical phrase
was he oikoumene (ge) "the inhabited (earth)." Septuagint uses both
kosmos and oikoumene. Kosmos also was used in Christian religious
writing with a sense of "worldly life, this world (as opposed to the
afterlife)," but the more frequent word for this was aiōn, literally
"lifetime, age."
The word cosmos often suggested especially "the universe as an
embodiment of order and harmony." also from c. 1200
See some commentaries for better understanding of the phrasing on 1Peter 3:3:
Ellicott writes,
—The passage shows that the Asiatic Christians were not all of the poorer classes. Many of the wealthy Jewesses had joined them. The wealth of the Ephesian Christians about this time may be gathered from 1Timothy 2:9, and of the Laodiceans from Revelation 3:17. Two things are to be noted about the advice here given. (1) It is not intended directly as a corrective of vanity. St. Peter is not bidding them beware of love of dress, although (as Bengel points out) the three words of “plaiting,” “wearing” (literally, putting round oneself), and “putting on,” are intended to convey the notion of elaborate processes in which time is wasted. But the main thought is, How are the husbands to be attracted? Not, says St. Peter, by any external prettiness of adornment, but by inward graces. (2) The Apostle is not forbidding the use of gold, &c. Leighton (himself something of a precisian) says, “All regard of comeliness and ornament in apparel is not unlawful, nor doth the Apostle’s expression here, rightly considered, fasten that upon the adorning he here speaks of. He doth no more universally condemn the use of gold for ornament than he doth any other comely raiment, which here he means by that general word of putting on of apparel, for his ‘not’ is comparative; not this adorning, but the ornament of a meek spirit, that rather, and as much more comely and precious; as that known expression (Hosea 6:6), ‘I will have mercy, and not sacrifice?”
Pulpit Commentary
Verse 3. - Whose adorning let it not be that outward adorning of plaiting the hair. A common Hebraism, like our Lord's injunction in John 6:27, "Labor not for the meat which perisheth, but for that meat which cndureth unto everlasting life." St. Peter does not forbid the moderate use of ornaments, but asserts their utter worthlessness compared with Christian graces. The ladies of the time seem often to have had their hair dressed in a very fantastic and extravagant manner. And of wearing of gold; rather, golden ornaments. Or of putting on of apparel. This verse shows that, although the mass of believers at this time belonged to the poorer classes, yet there must have been a proportion of persons of rank and wealth among the Christians of Asia Minor (comp. 1 Timothy 2:9; Revelation 3:17). 1 Peter 3:3
We see that the in these verses is the same as John 6:27 "Do not work for the food that perishes, but for the food that endures to eternal life" (ESV), it does not mean it is forbidding work for food in an absolute sense, but it is teaching about where your focus should be. As for the Biblical norm on modesty for women, we should remember the context that these words are written to Pagan converts, i.e. the Romans and Greeks, who were known to be sexual, indecent, immodest when it comes to the culture about women. The Western culture is derived directly from the Greco-Roman culture, hence, the surprise and shock of some believers when reading such passages in the New Testament warning against makeup, and indecent unnatural roles for women. The Jewish women did not wear any adornment, perfume etc. These things were considered characteristic of prostitutes in the Eastern and far Eastern cultures, from Israel, India, to China and Philippines. The writers of the Bible were Jews, from a particular culture and religion; we must therefore keep this cultural background when interpreting the text.
Searching on advance search on google books, we see the quote from Peter R. Rodgers · 2017, 1 Peter: A Collaborative Commentary - Page 82
