Lineal

adjective

1. (family) Of a family relationship that includes mothers, fathers, daughters, sons, grandparents, grandchildren, etc., but not siblings; as opposed to collateral.
2. Inheriting by direct descent; having the right by direct descent to succeed (to).
3. Composed of lines; delineated.

   "lineal designs"

4. In the direction of a line; of a line; of or relating to a line; measured on, or ascertained by, a line; linear.

   "lineal magnitude"