A cyst is a small growth that forms in the body. That squishy, fluid-filled mass on your calf could be a cyst.
The word cyst entered English in the 18th century by way of the Latin word cystis, tracing all the way back to the Greek word kustis, meaning “bladder.” Like your bladder, a cyst is sort of like a small pouch, one that’s typically filled with liquid. Unlike the bladder, however, a cyst is closed, meaning the liquid can’t get out. A cyst is often an abnormal formation in the body, so doctors often remove them.