effusion

noun

1. a pouring forth
2. unrestrained or emotional expression in speaking or writing
3. 1. an escape of fluid that is bloody, serous, etc. into body cavities or tissues
   2. this fluid
4. the passage of a gas under pressure through an orifice whose size is smaller than the mean free path of the gas molecules, as in measuring low vapor pressures

Origin: ME & OFr < L effusio: see effuse