哀鸣 combines 哀 (sorrow) and 鸣 (to sound/cry), describing a long, mournful sound made by animals or people in distress. As a noun it refers to the sound itself (a wail, a plaintive cry); as a verb it means to make that sound (to wail, to cry plaintively). You'll encounter it in literary or news contexts — for example, describing a wounded animal's cry or a figurative 'cry of despair' from a group facing hardship.