descending in a direct line from an ancestor; hereditary; derived from ancestors; -- opposed to collateral; as, a lineal descent or a lineal descendant.-inheriting by direct descent; having the right by direct descent to succeed (to).-composed of lines; delineated; as, lineal designs.-in the direction of a line; of or pertaining to a line; measured on, or ascertained by, a line; linear; as, lineal magnitude.