Noun

1. A dog
2. A dog of mixed breed, a mongrel
3. A bulge, an enlarged part

   "There's a pooch in the plastic where it got too hot."

4. A distended or swelled condition.

   "Her left sleeve has more pooch at the shoulder than the right."

Verb

1. To distend, to swell or extend beyond normal limits; usually used with "out":

   "Inflate that tire too much and the tube may pooch out of the cut in the sidewall.