Haematology – The scientific study of blood

(Pronounced hee-muh-to-luh-jee)

We know that ology is "the study of" (see ology) 

Haema = blood, which can be remembered using the following mnemonic:

He decided he must (haema) give blood every week.

So, haematology must mean the study of blood. 

Examples of  haematology in a sentence

He went to university to study haematology. 

The doctor couldn't figure out what was wrong with her, so he sent her to the haematology clinic to see a specialist.

She stopped by the haematology lab to see whether her patient's blood tests were done.