hyposmolality

noun

hy·​pos·​mo·​lal·​i·​ty ˌhī-ˌpäz-mō-ˈlal-ət-ē 

variants or hypoosmolality

ˌhī-pō-ˌäz- 

plural hyposmolalities

: the condition especially of a bodily fluid of having abnormally low osmolality