The term 'Sound of an Empty Stomach' can be summarized by two crossword solutions: GROWL (5 letters) and GRO (3 letters). GROWL is a low, guttural sound that is often associated with animals such as bears or lions. It is also used to describe the sound of an empty stomach when someone is hungry. GRO is a less intense version of a GROWL, and is usually used to express displeasure or annoyance. Both words are commonly used to describe the sound of an empty stomach.