The phrase "slimmer waist" refers to having a narrower or thinner waist, indicating a reduction in the width or size of the midsection of the body. Full definition
And it's designed to be flattering: «It has a lot of color blocking to give the illusion of slimmer waist and thighs, which I love,» she says. (people.com)
If you've to get ready for work, pull on a cardigan over a shirt paired with slim waist pants. (zunera-serena.com)
If you want to get slim waist it is vital to train your lower back. (abmachinesguide.com)