holograph (n.)

"document written entirely by the person from whom it proceeds," 1620s, from Late Latin holographus, from Greek holographos "written entirely by the same hand," literally "written in full," from holos "whole" (from PIE root *sol- "whole, well-kept") + graphos "written," from graphein "to write" (see -graphy). Modern use, with reference to holograms, is a 1960s back-formation from holography.