Abaci may refer to:

• Muazzez Abaci, Turkish singer
• Abaci, Göynücek, village in the District of Göynücek, Amasya Province, Turkey

Liber Abaci (1202, also spelled as Liber Abbaci) is a historic book on arithmetic by Leonardo of Pisa, known later by his nickname Fibonacci. In this work, Fibonacci introduced to Europe the Hindu-Arabic numerals, a major element of our decimal system, which he had learned by studying with Arabs while living in North Africa with his father, Guglielmo Bonaccio, who wished for him to become a merchant.