See also: くじん, ぐしん, and ぐじん

Japanese

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For pronunciation and definitions of くしん – see the following entries.
苦心
[noun] pains, efforts, hard work
[verb] make strenuous efforts, be at pains to, struggle to
(This term, くしん (kushin), is the hiragana spelling of the above term.)

(The following entry is uncreated: 苦辛.)