According to Wikipedia, the word "bikini" was coined by its inventor, Louis Réard, who was competing with a rival designer to create "the world's smallest swimsuit." He named it after Bikini Atoll, where testing on the atomic bomb took place, because he believed "the suit's revealing style would create a stir among people similar to America's atomic bombing of Japan the previous summer." (Um, weird... but it sure is still creating stirs!) The garment he created resembled women's underwear, and he could not find a model daring enough to wear his design, so he had to hire a nude dancer to model it.
And according to Merriam-Webster, a bikini is "a woman's scanty two-piece bathing suit." (I will ignore the second definition - a man's brief swimsuit - for the sake of my argument, and because America has agreed we're against those.) The definition of "scanty," FYI, is "limited or less than sufficient in degree, quantity, or extent."
So, what we've learned here is that by etymology and current definition, "bikini" denotes sexy, and "kid bikini" connotes creepiness.
What is okay, however, and where the debate gets muddled, is two piece swimsuits for girls. The difference? More coverage and less allusion to lingerie and cleavage. Following this logic, judgment of recent controversies becomes rather simple:
Apparently people were up in arms about this picture of Suri Cruise... there are plenty of creepy things about her parents, but dressing her in this two-piece is not one of them.
These swimsuits marketed by Elizabeth Hurley, however, are most definitely creepy. I even feel creepy posting them... and don't even get me started on the leopard print.
I actually don't mind Gwyneth's as much, but again, I just find the words "kid" and "bikini" being used together inappropriate, and there's something about the way the models are posed in the first picture that gives me the uneasies.
So there you have it. I'm sorry Gwyneth, but for the sake of ending this debate and curbing creepiness, "kid bikinis," no matter how relatively tame, need to go out of style. For good.