GERD is Gastroesophageal Reflux Disease. It is a condition where acid from the stomach flows upwards into the esophagus. Heartburn is the most common symptom of GERD, and the only one that almost everone experiences at some point in their life. It is classified as a disease when it happens frequently enough to interfere with a persons normal life or to damage the esophagus

In many cases, it is caused by excess relaxation of the sphincter that keeps the top of the stomach closed while food is not going through it.

Severe cases can damage the esophagus badly. The damage can has been linked to esophageal cancer.

In Norse Mythology, Gerd is an earth goddess and the goddess of light, beautiful giantess, wife of Freyr, and daughter of Gymir. She is said to be so lovely that her uncovered arms light up the skyand the sea when the world is dark.

She never wanted to marry Freyr and after she refused all of his proposals he sent his servant, Skrinir, to woo her and present her with eleven golden apples and the ring Draupnir. When she still refused, Skirnir threatened to cover the earth with ice with Freyr's sword and use magic to doom Gerd to a life full of misery and sadness. After all of the threats, she finally agreed to meet Freyr in the forest Barri and give herself to him in nine days. She later became his wife and their marriage symbolizes the union of the earth and the sky.

Gerd is also known as Gerda and Gerdhr.

Sources:
http://www.pantheon.org/articles/g/gerd.html