Peace and many blessings,
Excellent question. I’m going to have to be bias here and say that according to existential Quranism, it is what you understand it to be. Allah is not concerned with how others define it, although it does help to study Arabic grammar, but initially, Quran is meant to speak directly to you. Hence, Allah is speaking to you regarding this notion of “jalaabibihinn.”
If you take it to mean that Allah is suggesting that one cover his or her body in this jelbab like material, then by all means, do so. However, if you find it to mean this notion of garmenting the self, or covering the self, then that is understandable. There are others, however, that would suggest that it is an addressing of our women in the community to observe the notion of garmenting the self; hence, addressing the social issue of modesty.
tagged as: am17am. questions. existential quranism. arabic.