呵呵

Onomatopoeic. Compare English haha. Partly replaced by modern 哈哈 (hāhā) due to sound shift 呵 (MC xa) > 呵 (hē).

呵呵

1. (onomatopoeia) sound of laughter

   • 近作小詞，雖無柳七郎風味，亦自是一家。呵呵！ [Classical Chinese, trad.]
     近作小词，虽无柳七郎风味，亦自是一家。呵呵！ [Classical Chinese, simp.]

     From: c. late 11th century, Su Shi (蘇軾), Letter to Xianyu Zijun (《與鮮于子駿》)

     Jìn zuò xiǎocí, suīwú Liǔ Qīláng fēngwèi, yì zìshì yījiā. Hēhē!

     Recently I wrote some little ci poems. Though hardly comparable to Mister Liu's style, they're in my own character. Haha!

2. (onomatopoeia, ironic) sound of derisive or perfunctory laughter

   呵呵，你不行。  ―  Hēhē, nǐ bùxíng.  ―  Heh, you aren't up to it.

呵呵

1. an expressive suffix for adjectives

Ultimately from Middle Chinese 呵呵 (MC xa xa).

First cited to a text from roughly 900 CE.^[1]

• (Tokyo) かか (Atamadaka – )^[2][3]
• IPA^(key):

呵(か)呵(か) • (kaka) 

1. (literary) laughingly

   Synonyms: あはは (ahaha), からから (karakara)

• 呵(か)呵(か)然(ぜん) (kakazen, “laughing”, adjective)
• 呵(か)呵(か)大(たい)笑(しょう) (kaka taishō, “a belly laugh, a guffaw”, noun)