ku (Chinese)

For the Chinese adjective and morpheme 「苦」 (kǔ; in translation: "bitter; hardship"), the 「デジタル大辞泉」 (in translation: "Digital Daijisen") kanji entry gives the Japanese kun readings 「にがい」 (nigai; in translation: "bitter") and 「にがる」 (nigaru; in translation: "to show displeasure"); it says the character is taught in the year 3 of elementary school. Its first character sense is 『味がにがい。「苦汁・苦味／甘苦」』 (in translation: "The taste is bitter; examples include bitter juice, bitterness, and sweet-and-bitter"), placing the taste sense first. The Chinese dictionary 「漢典」 (in translation: "Handian") (zdic.net) likewise begins its basic explanation of 「苦」 with 『像膽汁或黃連的滋味，與「甘」相對。』 (in translation: "A taste like bile or Coptis root, opposed to sweet"), again placing the taste sense first.

The senses of 「苦」 (kǔ; in translation: "bitter; hardship") extend widely into metaphor. 「デジタル大辞泉」 (in translation: "Digital Daijisen")’s 「字義２」 (in translation: "second character sense") is 『精神的・肉体的につらい思いをする。くるしい。くるしみ。』 (in translation: "To experience mental or physical hardship; painful; suffering"), illustrated by many compounds such as 「苦学・苦境・苦行・苦心・苦戦・苦痛・苦悩・苦楽・苦労」 (in translation: "hard study, adversity, asceticism, effort, struggle, pain, anguish, hardship and joy, toil"). Its 「字義３」 (in translation: "third character sense") denotes a bitter or displeased quality, as in 「苦言・苦笑・苦情」 (in translation: "frank criticism, wry smile, complaint"). 「漢典」 (in translation: "Handian") also gives a sense of feeling distressed and the sense 『爲某種事所苦。例如：苦雨、苦旱。』 (in translation: "To be troubled by something; examples: excessive rain and drought"), documenting use for being afflicted by something.

「苦」 (kǔ; in translation: "bitter; hardship") is also listed as a noun. Following a sense of mental and physical distress, 「デジタル大辞泉」 (in translation: "Digital Daijisen") gives a Buddhist sense, one of its basic concepts: 『煩悩や悪い行為などの報いとして受ける心身の苦しみ。』 (in translation: "Mental and physical suffering received as the consequence of worldly desires or bad actions"). The Japanese noun read 「にが」 (niga; in translation: "spiteful or sarcastic words"), by contrast, is defined as 『《形容詞「にがい」の語幹から》憎まれ口。いやみ。にがぐち。』 (in translation: "From the stem of the adjective nigai [bitter]: a spiteful remark, sarcasm, or bitter words"), with an example from 「浄・矢口渡」 (the jōruri play Yaguchi no Watashi). 「漢典」 (in translation: "Handian") additionally gives a sense of persevering and exerting oneself, with the example 「吃苦耐勞」 (in translation: "endure hardship and work without shirking"), and a sense of suffering or poverty with 「苦厄」 (in translation: "hardship and misfortune"), adding uses that describe an attitude of enduring hardship.

Compounds also show both senses of 「苦」 (kǔ; in translation: "bitter; hardship"). The Ministry of Education’s 「重編國語辭典修訂本」 (in translation: "Revised Mandarin Chinese Dictionary") lists three senses of 「甘苦」 (gānkǔ; in translation: "sweet and bitter; joys and hardships"): sweet and bitter tastes; figurative favorable and adverse treatment or joys and hardships; and hardship alone. For its second sense it cites 『燕王弔死問孤，與百姓同甘苦。』 (in translation: "The king of Yan mourned the dead and cared for orphans, sharing joys and hardships with the people") from 「史記」 (in translation: "Records of the Grand Historian"). For 「苦澀」 (kǔsè; in translation: "bitter and astringent; inner suffering"), it lists both a bitter, astringent taste and a figurative sense, 『形容內心很痛苦。如：他臉上盡是苦澀的表情。』 (in translation: "Describes great inner pain; for example, his face bore an expression full of bitterness"). The 「説文解字」 (in translation: "Shuowen Jiezi") cited by 「漢典」 (in translation: "Handian") explains that the character 「苦」 (kǔ; in translation: "bitter; hardship") originally referred to a plant called 「苓」 (líng), linking its origin to a plant name.