Minor characters are sometimes called, well, just the opposite, "flat".

正好相反，次要角色通常被称为“扁平人物”。

youdao

The opposite of smooth and flat.

我知道这个肆意的反义词，就是平滑。

youdao

Farsightedness is the opposite, in a way: A shorter-than-average eyeball or too-flat cornea focuses light behind the retina instead of on it, making near vision and sometimes distant vision blurry.

远视在某种程度上则相反，是较正常短些的眼球前后径或者太平坦的角膜使光线聚焦于视网膜后而不是之上，这导致近景视觉模糊和有时的远景视觉模糊;

youdao

It moved through hoods, beanies and "Cat in the Hat" hats on to baseball caps first turned sideways and then with a flat brim (the polar opposite of the redneck and preppy artfully turned trend) and the current reinvented trend for "the bucket, " preferably from Louis Vuitton or Ralph Lauren.

WSJ: Tina Gaudoin on Style: The Hat Is On | The Top Winter Accessories

Mr. Graham shows me a ballet step with fins, the legs moving outward in opposite directions, the feet flat, slowing the ascending diver, turning the body from side to side to see the reef.

WSJ: The Ultimate Breathtaking Dive

The terrain in the Charlevoix region was very different from what I had experienced on the opposite banks: the roads so far had been flat or gently curving, here they snaked and rolled, dramatically rising and falling.

BBC: Canada��s greatest cycling trail