|1||v.||loose; allow; relax; let go; let fly; be indulgent; release; set free|
|2||adj.||vertical; perpendicular; longitudinal; lengthwise|
|4||idiom||even if; granted that|
http://humanum.arts.cuhk.edu.hk/Lexis/lexi-mf/search.php?word=%E7%B8%B1 wrote that "可能由於絲織品是由直線和橫線編織而成，故「縱」後來表示「直」，與「橫」相對。" Here's my translation in English — perhaps because silk fabrics are woven from straight and horizontal threads, 「縱」means straight, as opposed to "horizontal".
But the website did not elaborate 3 and 4? How is "although" related to "本義是一種絲織品。"?
How is "even if; granted that" related to "本義是一種絲織品。"?