A diagram or chart showing family relationships or lineage; a family tree or pedigree.
祖先の系図を図書館で調べた。
I searched the family tree of my ancestors at the library.
その犬はきちんとした系図がついているので純血種だとわかった。
The dog had a proper pedigree, so I could tell it was a purebred.
この小説は貴族の系図をたどる物語だ。
This novel traces the family tree of a noble family.