...and the technical term is "Ptosis."
Six months ago, I wouldn't have thought twice about saying "drooping" or "sagging." They describe a state of being (regarding breasts, in this case) that I didn't blink at. Say those words and everybody knows what you're talking about. Unfortunately, words like droop or sag can be quite crushing to someone who is just coming up in the world or where the terms are used only with a negative connotation. And, realistically, if you look at the synonyms for them, there doesn't appear to be any "good" words; though I do like languid--makes me think of an easy-going Summer day but I digress.
The term most accepted by those who participate in discussion about breasts on the subreddit ABraThatFits is "pendulous." I have no problem switching to the accepted term. Why would I fight to use droop or sag? I have no intellectual ownership of them. I gain nothing by insisting upon using them? I would ask others, if you don't already use the term "pendulous", try to do so.
I once equated the term comparison of "sagging" and "pendulous" to that of "retarded" and "special needs", hoping to make a point. It didn't appear to have worked. Folks can be offended by the term "sagging" just as folks can be offended by the term "retarded." Why not use the less offensive term if you lose nothing in doing so?
So, what is "pendulous"? It's most literal definition, according to dictionary.com: hanging down loosely (with an example of "pendulous blossoms"--now that sounds quite pretty...makes me think of lilacs :) )
In terms of breasts, if they're pendulous, most of the breast tissue is below the Infra-Mammary Fold (IMF). For those who have breasts that aren't pendulous, this condition might be associated with someone who has gained and lost a large amount of weight, someone who exercises without a bra, or someone who is aged. Though commonly true, that is not always the case. Anyone, at any age or level of maturity, can have pendulous breasts. It's all about genetic, biological, and physiological structure. There might be other -ogical things involved but it's late at night and none come immediately to mind.
To be pendulous doesn't always have to be large breasts either. A person can be on the smaller end of the spectrum and still have pendulous breasts. I had a customer a few years back who was quite thin. She had pendulous breasts that were made up of just the skin. There was very little fat within the breast. And they were positioned below the IMF. Pendulous. Conversely, I've had customers who had very large, non-augmented breasts, that were not.
Again, it's just a matter of how the cells in your body are configured. They are neither good nor bad. They just are and they are you and you are a beautiful, unique combination of traits.