What is the right adjective to describe meat?
The sentence is: "We stopped eating our sandwiches when we realised the meat was ... " What adjective should I use to say that the meat was spoiled/smelled bad?
Rotten/rank/foul or any other adjectives?

Question

Answer

Most English speakers would describe meat that had a bad TASTE by saying, 
"the meat has gone bad",  "the meat has gone off" or "the meat tastes rancid".
The word "rotten" would be used for food is in a noticeable STATE OF DECAY.
Words such as putrid, foul and rank would be used to describe a bad SMELL.

Hope this helps

Answer

I agree with Naomi’s answer, but I would add that your suggestion of “was spoiled” would sound very natural and that “rancid” is fairly uncommon in U.S. English.

لا تفوّت فرصة تعلّم لغة جديدة وأنت مرتاح في منزلك. تصفّح مجموعتنا المختارة من مدرّسي اللغات ذوي الخبرة وسجّل في درسك الأول الآن!