effusion

1. (chemistry, physics) Process of gases passing through a hole or holes considerably smaller than the mean free path of the gas molecules.countableuncountable

2. (figurative, by extension) An outpouring of speech or emotion.Examples: "1930; George S. Kaufman, Morrie Ryskind, Bert Kalmar, Harry Ruby; Animal Crackers, Paramount Pictures Captain Spaulding: My friends, I am highly gratified by this magnificent display of effusion […]"; "The housekeeper, a very decorative brunette of thirty-five with a pseudo-English accent, greeted him with a mixture of grateful effusion and condescending patronage."broadlycountablefigurativelyuncountable

3. (medicine) The seeping of fluid into a body cavity; the fluid itself.Examples: "pleural effusion"countableuncountable