Let $\mathscr{C}$ be a cocomplete category and $f: I \to J$ be a functor between small categories. Typically, the left Kan extension along $f$ is denoted by $\operatorname{Lan}(f) : \operatorname{Fun}(C, I) \to \operatorname{Fun}(C, J)$. Dually, the right Kan extension is typically denoted by $\operatorname{Ran}(f)$.
Does anyone know what $\operatorname{Lan}$ stands for? "L" (resp. "R") probably stands for "left" (resp. "right") and maybe "a" somehow stands for "adjoint"?