Blubber is the thick layer of fat that keeps whales and other large swimming mammals warm in the cold water. Inuits and other northern people have traditionally relied on eating blubber.
Based on marine animal blubber, some people describe human fat as blubber too — often in a derogatory way. When blubber is a verb, it means to sob uncontrollably: "The little girl sat down and started to blubber after skinning her knee." Blubber was originally spelled blober, meaning "a bubble" or "bubbling water," which led to the "crying" meaning of the word. In the 15th century, it also meant "jellyfish" and "whale oil."