H₂O

• English: (US) IPA^(key): /ˌeɪt͡ʃtuːˈoʊ/
• French: IPA^(key): /aʃ.dø.zo/
• German: IPA^(key): /haːt͡svaɪ̯ʔoː/, [haːt͡sʋaɪ̯ʔoː]

H₂O

1. (generally) Water (even if not chemically pure).
   • 1992, John R. Searle, The Rediscovery of the Mind (in English), →ISBN, page 157:

     A man may believe, for example, that the star in the sky is the Morning Star without believing that it is the Evening Star. A man may, for example, want to drink a glass of water without wanting to drink a glass of H₂O.

2. (chemistry) A molecule of water.

• IUPAC recommends that deuterium should be named by the chemical symbol "²H", not "D".^[1] Therefore, even heavy water (often called D₂O) should properly be called H₂O; ²H₂O to be precise. Likewise, super-heavy water should be called ³H₂O, not T₂O.

• H₃O⁺, H₃O, hydronium
• OH^-, OH, hydroxide
• 2H₂O, H₄O₂, H₃OOH, H₃O-OH, hydronium hydroxide

• D₂O (“heavy water”)
• DHO (“semi-heavy water”)

• H₂O₂ (“hydrogen peroxide”)
• English DHMO (“dihydrogen monoxide”)

Two H initials (Hishammuddin Hussein) represented by H₂ + O for Onn, chosen to humorously match the chemical formula for water.

• (US) IPA^(key): /ˌeɪt͡ʃtuːˈoʊ/

H₂O

1. (Malaysia, Internet slang, humorous, politics) Hishammuddin Hussein Onn, Malaysian politician and son of Hussein Onn, third prime minister of Malaysia.