The phrase "oversized silhouette" refers to a clothing or object that appears larger or bigger than it usually would. It describes something that has a shape or form that is much larger than expected. Full definition
Let's move on to the fashion side of things, 2016 winter style goals featuring oversized silhouettes, monochrome palettes, and minimalism. (alice.typenu.com)
This collection stays true to the idea of uniform pieces for a man's wardrobe, but the slightly oversized silhouette adds a fresh update. (inc.com)
Or how about oversized silhouettes, furry materials and monochromatic looks in every other style there is? (thefashionfolks.com)