Definitions
1.adjective(family) Of a family relationship that includes mothers, fathers, daughters, sons, grandparents, grandchildren, etc., but not siblings; as opposed to collateral.
2.adjectiveInheriting by direct descent; having the right by direct descent to succeed (to).
3.adjectiveComposed of lines; delineated."lineal designs"
4.adjectiveIn the direction of a line; of a line; of or relating to a line; measured on, or ascertained by, a line; linear."lineal magnitude"