Divisible group 可除群
In mathematics, especially in the field of group theory, a divisible group is an abelian group in which every element can, in some sense, be divided by positive integers, or more accurately, every element is an nth multiple for each positive integer n. Divisible groups are important in understanding the structure of abelian groups, especially because they are the injective abelian groups.
：对每个正整数 
及元素 
，存在 
使得 
。等价的表法是：
。事实上，可除群恰好是 
上的内射模，所以有时也称之为内射群。