- 1
If someone is a lineal relative, they sit on the straight family line: a parent, a , a child, a . An uncle or a cousin is still family, but not lineal — they sit to the side of that straight line. You will see this word in law and in careful writing, often in the phrase lineal . It is not a daily-talk word. Though actually, it looks like linear, and they are sister words from the same Latin “line,” but they are not the same. Linear is about a straight line in space, or about steps in order. Lineal is about blood in a family.
直系的（直系血親，對照旁系）
組成From Old French lineal, from Latin līneālis: līnea (a line) + -ālis (makes an adjective). On the surface, line + -al. It is a doublet of linear: same Latin source, two English words.
原始詞典資料5 筆記錄
以下是外部詞典記錄的用法，原文照列，我們還沒有寫成教學內容。上面的說明才是我們自己寫的；有些用法可能上面已經講過了。
linealadj/ˈlɪni.əl/
- 1
Pertaining to lines; consisting of lines.
- 2
anthropologyhistoryhuman-sciencesRelating to aspects of lineage, such as descent, succession, inheritance or consanguinity.
- the prime and ancient right of lineal succession
- Oh that your Brows my Laurel had ſuſtain'd, / Well had I been depos'd, if You had Reign'd! / The Father had deſcended for the Son; / For only you are lineal to the Throne.
- 3
In the direction of a line; measured or ascertained by a line.
- lineal magnitude
- 4
artartsLine-drawn; composed of lines.
- lineal designs
- 5
mediapublishingtypographySans serif.
資料來源：英文維基詞典 English Wiktionary（CC BY-SA 4.0）。 原文照列，未經改寫。