Also haema‑ and haemat(o)-.
Greek haima, haimat‑, blood.
Many medical terms contain these forms; in the US, they all begin hem‑. A few examples of haemo‑: haemorrhage (Greek rhēgnunai, burst), a profuse escape of blood from a ruptured blood vessel; haemoglobin, a red protein responsible for transporting oxygen in the blood, of which the iron-containing part is the haem (US heme); haemophilia (Greek philia, fondness or undue inclination), a medical condition in which the blood does not clot properly.
The longer form haemato‑ is found in haematocrit (Greek kritēs, judge), the ratio of the volume of red blood cells to the total volume of blood, or an instrument for measuring this; haematemesis (Greek emesis, vomiting) is vomiting of blood; haematuria is the presence of blood in urine.
The important ore of iron called haematite was so named - from Greek haimatitēs (lithos), blood-like (stone)—because it is a reddish-black mineral.
See also sangui‑.