What is the meaning of Isotopic?

of, or relating to isotopes

Of two presemifields ${\displaystyle \mathbb {S} }$ and ${\displaystyle \mathbb {S} '}$ of characteristic ${\displaystyle p}$, when there exists three linear maps ${\displaystyle g_{1}}$, ${\displaystyle g_{2}}$, and ${\displaystyle g_{3}}$ from ${\displaystyle \mathbb {S} }$ to ${\displaystyle \mathbb {S} '}$ such that ${\displaystyle g_{1}(x\cdot y)=g_{2}(x)\circ g_{3}(y)}$ for all ${\displaystyle x,y\in \mathbb {S} }$.

Source: wiktionary.org