Abo may refer to:

• Abo of Tiflis (–786), an Arab East Orthodox Catholic saint
• Abo (name), an Arabic or Hebrew male name
• An offensive reference to Aboriginal Australians

The ABO blood group system is the most important blood type system (or blood group system) in human blood transfusion. Found on platelets, epithelium, and cells other than  erythrocytes, AB antigens (as with other serotypes) can also cause an adverse immune response to organ transplantation. The associated anti-A and anti-B antibodies are usually IgM antibodies, which are produced in the first years of life by sensitization to environmental substances, such as food, bacteria, and viruses. ABO blood types are also present in some other animals, for example rodents and apes, such as chimpanzees, bonobos, and gorillas.

Abon (Abõ) is a Tivoid language of the Cameroons.

Turku (; ) is a city on the southwest coast of Finland at the mouth of the Aura River, in the region of Southwest Finland. Turku, as a town, was settled during the 13th century and founded most likely at the end of the 13th century, making it the oldest city in Finland. It quickly became the most important city in Finland, a status it retained for hundreds of years. After Finland became part of the Russian Empire (1809) and the capital of the Grand Duchy of Finland was moved to Helsinki (1812), Turku continued to be the most populous city in Finland until the end of the 1840s, and it remains a regional capital and an important business and cultural center.