"Obstructed Constipated Obstipated"

I'm not sure how the rest of the world defines these but there are differences.

If a cat 'can't poop' and has a BIG poop remnant blocking the anus, but the rest of the digestive tract is "pretty okay" I'd call that OBSTRUCTED - quite often, clearing the obstruction is "pretty easy" and the cats can go on motility modifiers, soluble and insoluble fiber or even laxatives to keep things 'moving' and not form another big fecolith that blocks the exit. (Anus)

If a cat 'can't poop' and the lower bowel is full of large, hard(ish) poop and a laxative and some fluids "does the trick" and the cat or dog poops, then it was obstipated.

If a cat or dog 'can't poop' and all of the above are true and a laxative and some fluids DO NOT MOVE THINGS ALONG then I call that 'constipated' and it will require an enema or even 'digital' (glove) removal of the offending bowel remnants.

QUITE OFTEN the owner thinks a dog or cat "Can't poop" and there's ACTUALLY nothing in there. In fact the colon is SPASTIC or IRRITATED (for exam inflammatory bowel disease) the dog FEELS LIKE it has to poop, holds that posture repeatedly and produces NO poop. On those it's easy, I'll do my exam and I'll find zero poops in the dog. It's cleaned out but STILL "has to poop" so it looks constipated / obstipated.

That's colitis.