When was the concept of a "homomorphism" of algebraic structures first introduced?
Steinitz' 1910 paper Algebraic Theory of Fields is often pointed to as the first true work of abstract algebra, yet the concept of homomorphism is lacking in this work. For example, here is Steinitz' definition of isomorphism (page 172):
Two systems $\frak{S}_1$, $\frak{S}_2$ with double composition are called isomorphic or from the same (composition) type if it is possible to relate their elements unambiguously to one another, so that to the sum and product of any two elements of one system is assigned every time the sum and the product of the corresponding elements in the other; the relation itself is called an isomorph or isomorphism.
This definition seems clumsy by modern standards. I'm wondering who improved it and when.