An invertible sheaf $\L$ on a scheme $X$ is called ample if for any coherent sheaf $\F$ , $\F\otimes\L^n$ is generated by global sections for sufficiently large $n$ .

An invertible sheaf is ample if and only if $\L^m$ is very ample for some $m$ ; this is very often taken as the definition of ample, which can be surprising.