薬 (Kangxi radical 140, 艸+13, 16 strokes, cangjie input 廿戈人木 (TIOD), composition ⿱艹楽)

• 𣟿, 𬟥, 𬌖, 𫊚

• Kangxi Dictionary: not present, would follow page 1062, character 44
• Dai Kanwa Jiten: character 32188
• Hanyu Da Zidian (first edition): not present, would follow volume 5, page 3303, character 5
• Unihan data for U+85AC

(Third grade kyōiku kanji, shinjitai kanji, kyūjitai form 藥)

1. medicine, drug
2. chemical

• Go-on: やく (yaku, Jōyō)
• Kan-on: やく (yaku, Jōyō)
• Kun: くす (kusu, 薬)、くすり (kusuri, 薬, Jōyō)
• Nanori: み (mi)

From Old Japanese. Cognate with the kusu root of adjective 奇し (kusushi, “mystical”),^[1] from the way that drugs and medicines would have mystical effects.

• IPA^(key): [kɯ̟sɨ]

薬(くす) • (kusu) 

1. a medicine or drug

Only used in compounds.

From Proto-Japonic *kusori. Derivation from kusu above. Appears to be the 連用形 (ren'yōkei, “continuative or noun form”) of unattested verb kusuru “to have a mystical effect”.

• (Tokyo) くすり [kùsúrí] (Heiban – [0])^[3][4][2]
• IPA^(key): [kɯ̟̊sɨɾʲi]

• (Kyoto) くす​り [kùsúꜜrì] (Teiki)^[2]

薬(くすり) • (kusuri) 

1. a substance with mystical properties, especially one that has an effect on the body, health, or lifespan
2. a medicine or drug, a pharmaceutical
3. a chemical, generally toxic and used for its effect on living organisms, such as insecticide or herbicide
4. a substance that has a beneficial effect in improving or maintaining one's health
5. (figurative) something that has a beneficial effect in correcting one's mistakes
6. Short for 釉薬 (uwagusuri): a glaze or enamel applied to ceramics
7. gunpowder (from the “mystical substance” sense, and the second character in the word 火薬 (kayaku, “gunpowder”))
8. (figurative) a small bribe

The medicine sense is probably the most common in modern Japanese.

From Middle Chinese 藥 (MC yak). Compare modern Cantonese 藥／药 (joek6).

• (Tokyo) やく [yáꜜkù] (Atamadaka – [1])^[3][4][5]
• IPA^(key): [ja̠kɯ̟]

• (Kyoto) や​く [yáꜜkù] (Kōki)^[5]

薬(やく) • (yaku) 

1. (slang) a medicine or drug, especially a narcotic or other recreational drug

The slang meaning is generally limited to when the term yaku is used as a standalone noun. In compounds, yaku refers more generally to pharmaceuticals, or sometimes chemicals.