chylothorax

noun

chy·​lo·​tho·​rax -ˈthō(ə)r-ˌaks, -ˈthȯ(ə)r- 

plural chylothoraxes or chylothoraces -ˈthōr-ə-ˌsēz, -ˈthȯr- 

: an effusion of chyle or chylous fluid into the thoracic cavity