Does the notion of modular lattice have anything to do with the meaning of the word modular, in either English or mathematics?
A finite modular lattice is a finite graded lattice $L$ whose rank function $\rho$ satisfies $$ \rho(x)+\rho(y)=\rho(x\wedge y)+\rho(x\vee y) $$ for all $x,y\in L$. It has some equivalent definitions such like a finite lattice such that $$ x\vee (y\wedge z)=(x\vee y)\wedge z $$ for all $x,y,z\in L$ such that $x\le z$. The word modular means employing or involving a module or modules as the basis of design or construction in English, and relating to modulus in mathematics.