something that bulges out or is protuberant or projects from its surroundings
"the gun in his pocket made an obvious bulge"
"the hump of a camel"
"he stood on the rocky prominence"
"the occipital protuberance was well developed"
"the bony excrescence between its horns"
the increase in volume of certain substances when they are heated (often accompanied by release of water)
"The swelling of starch granules occurs rapidly when they are exposed to boiling water."
The state of being swollen.
"The swelling in her ankle made it difficult to walk without pain."
In plain English: Swelling is when an area of your body gets bigger and puffy because fluid builds up there after getting hurt or sick.
"He applied ice to reduce the swelling on his ankle after falling off his bike."
present participle of swell
"The river was rising rapidly, causing a swelling that threatened to overflow its banks."
In plain English: To swell means to get bigger and puff up, usually because of liquid building inside something.
"The river began swelling after days of heavy rain."