Backs-up definition

Once, when berrying, I met with a cat with young kittens in the woods, quite wild, and they all, like their mother, had their backs up and were fiercely spitting at me.

Memory foam mattress manufacturers make health claims about their products, but little medical evidence backs up these claims.

If bile cannot get out because the ducts are absent or blocked, it backs up into the liver (referred to as biliary stasis) and eventually into the rest of the body.

Besides infection, urine that backs up causes the ureter and the kidney to expand or dilate.