swell + -ing

source: By LucyHAE - Own work, CC BY-SA 3.0

an abnormal enlargement of a part of the body, typically as a result of an accumulation of fluid:

ふくらむ［腫れる］もの, 増大［膨張］(すること)

e.g. painless swellings may appear in the lower abdomen.

a natural rounded protuberance:

腫れ物, こぶ

e.g. the lobes are prominent swellings on the base of the brain.

becoming greater in intensity, number, amount, or volume:

隆起した, 腫れ上がった

e.g. the swelling ranks of Irish singer-songwriters.