LAB ALERT is a term used to describe a situation in which a dog is barking or making noise in an alarming manner. BARK is a four-letter word meaning to make a loud, sharp sound, usually as a warning or to express emotion. YELP is also a four-letter word meaning to make a short, sharp, high-pitched cry, usually as a sign of pain or alarm. GRR is a three-letter word meaning to growl, which is a low, guttural sound made by a dog or other animal to express anger or aggression.