五月雨

Compound of さ (sa-, prefix meaning "early") and an uncertain みだれ (midare), likely thought to be 水垂(みだ)れ (midare, “water fall”),^[1][2] where 垂(た)れ (tare) is the 連(れん)用(よう)形(けい) (ren'yōkei, “stem or continuative form”) of the verb 垂(た)れる (tareru). The tare changes to dare as an instance of rendaku (連濁).

The kanji spelling is jukujikun (熟字訓), from Satsuki-ame (see below).

• (Tokyo) さみだれ [sàmídáré] (Heiban – [0])^[2]
• IPA^(key): [sa̠mʲida̠ɾe̞]

五月雨(さみだれ) • (samidare) 

1. a heavy rain that occurs around the fifth lunar month; an early summer rain

   Synonyms: 卯の花腐し (unohana-kudashi), 梅雨 (tsuyu, baiu), 長雨 (nagame), 麦雨 (bakuu), 緑雨 (ryokuu)

   Antonym: 五月晴れ (Satsuki-bare)

   Hypernym: 雨 (ame)

   • 1603, Vocabvlario da Lingoa de Iapam (Nippo Jisho) [Vocabulary of the Language of Japan] (in Portuguese), Nagasaki, page 552:
     ^[3]

     Samidare. サミダレ (五月雨) Goguatno ame. (五月の雨) Nagaxi (ながし)と呼ばれる, [陰暦]五月の雨.

2. (figurative) that which repeats over and over without lasting long

• 五月(さつき)闇(やみ) (Satsuki-yami, “rainy season dark”)
• 五月雨(さみだ)る (samidaru)

五月雨(さみだれ) • (Samidare) 

1. a Shiratsuyu-class destroyer of the Imperial Japanese Navy during World War II (see Japanese destroyer Samidare (1935) on Wikipedia.Wikipedia )

   Hypernym: 白露 (Shiratsuyu)

2. a place name

• 五月雨(さみだれ)岩(いわ) (Samidare Iwa)
• 五月雨(さみだれの)滝(たき) (Samidare no Taki)

Compound of 五月, 皐月 (Satsuki, “fifth lunar month”) +‎ 雨 (ame, “rain”).

• (Tokyo) さつきあめ [sàtsúkíáꜜmè] (Nakadaka – [4])^[2]
• (Tokyo) さつきあめ [sàtsúkíꜜàmè] (Nakadaka – [3])
• IPA^(key): [sa̠t͡sɨ̥kʲia̠me̞]

五(さ)月(つき)雨(あめ) • (Satsuki-ame) 

1. a heavy rain that occurs around the fifth lunar month; an early summer rain.

   Synonyms: 梅雨 (tsuyu, baiu), 緑雨 (ryokuu)

   Antonym: 五月晴れ (Satsuki-bare)

   Hypernym: 雨 (ame)

   • 1603, Vocabvlario da Lingoa de Iapam (Nippo Jisho) [Vocabulary of the Language of Japan] (in Portuguese), Nagasaki, page 560:
     ^[3]

     Satçuqiame. (サツキアメ) (皐月雨) Samidare (五月雨)に同じ. [陰暦]五月の雨.