olemus
(1a) katkematu või regulaarselt katkeline punktijada
(1b) sirgjoon: ühemõõtmeline punktijada
(1c) ülekantud tähenduses, metafoorina

Wiktionary:
1. a path through two or more points (compare ‘segment’); a continuous mark, including as made by a pen; any path, curved or straight
1.1 (geometry) an infinitely extending one-dimensional figure that has no curvature; one that has length but not breadth or thickness
Synonym: straight line
10. the exterior limit of a figure or territory: a boundary, contour, or outline; a demarcation
14. a threadlike crease or wrinkle marking the face, hand, or body; hence, a characteristic mark
21. course of conduct, thought, occupation, or policy; method of argument; department of industry, trade, or intellectual activity
22. the official, stated position (or set of positions) of an individual or group, particularly a political or religious faction

näiteid
auxiliary line -- abijoon
contour line -- piirjoon
dash line -- kriipsjoon
dotted line -- punktiir
fashion line -- moejoon
lifeline -- elujoon
line art -- joongraafika
line chart -- joondiagramm, graafik
line graph -- joondiagramm, graafik
line movement -- joonliikumine, kulgliikumine
line of impact -- põrkejoon
line raster -- joonraster
line spectrum -- joonspekter
line style -- joone laad
line weight -- joone jämedus

piltlikult
https://www.quia.com/pages/line.html

https://www.pinterest.com/pin/281543714489977/

http://tgbasics.weebly.com/line-types.html

ülevaateid
https://www.britannica.com/science/line-mathematics

https://en.wikipedia.org/wiki/Line_(geometry)

https://mathworld.wolfram.com/Line.html

https://en.wikipedia.org/wiki/Curve

https://cadsetterout.com/drawing-standards/line-type-definitions/

vt ka
- alusjoon
- iseloomujoon
- joondiagramm
- joonelõpp
- lõikejoon
- mähisjoon
- papilllaarjoon
- rajajoon
- tunnusjoon
- tüübijoon
- visiirjoonestik