cyanosis

https://doi.org/10.1351/goldbook.10579

Bluish discoloration of the skin and mucous membranes due to excessive concentration of deoxygenated haemoglobin, owing to poor circulation or inadequate oxygenation of the blood.

Source:
PAC, 2016, 88, 713. (Glossary of terms used in developmental and reproductive toxicology (IUPAC Recommendations 2016)) on page 741 [Terms] [Paper]