Why does 丈夫 and 大丈夫 mean what they mean?


Looking at the individual kanji according to a dictionary:  
丈 means height, stature, length  
夫 means husband, man  
大 means big, great

They seem unrelated to what these words using the kanji mean:  
丈夫 means healthy, strong  
大丈夫 means safe, all right, okay

How did these words end up with these meanings?




A summary of the [gogen-allguide](http://gogen-allguide.com/ta/daijyoubu.html)
reference for 大丈夫:

丈 refers to a measure of height; about 3m by the 尺貫法{しゃっかんほう} system
(traditional Japanese standard) but less in older Chinese measures. One 丈
referred to the height of a man.

夫 here means 'man', so when these words were imported from China, 丈夫 meant a
fully grown man and 大丈夫 was a great/splendid man. From there 大丈夫 started to be
used to mean "exceptionally strong", "exceptionally reliable", "exceptionally
healthy", and from there the other meanings developed.

(大丈夫/丈夫 do not mean the same things in Chinese).




A summary of the [gogen-allguide](http://gogen-allguide.com/ta/daijyoubu.html)
reference for 大丈夫:

丈 refers to a measure of height; about 3m by the 尺貫法{しゃっかんほう} system
(traditional Japanese standard) but less in older Chinese measures. One 丈
referred to the height of a man.

夫 here means 'man', so when these words were imported from China, 丈夫 meant a
fully grown man and 大丈夫 was a great/splendid man. From there 大丈夫 started to be
used to mean "exceptionally strong", "exceptionally reliable", "exceptionally
healthy", and from there the other meanings developed.

(大丈夫/丈夫 do not mean the same things in Chinese).

