The Simple English Wiktionary has a definition for: H.

H is the eighth (number 8) letter in the English alphabet. The uppercase letter for H is H and the lowercase letter for H is h. The letter’s name is aitch (/ˈeɪtʃ/) or haitch (/ˈheɪtʃ/).

Meanings for H

• In chemistry, H is the symbol for hydrogen.
• In music, H is a note in the German system, meaning "B natural".
• In particle physics, H is the symbol for the Higgs boson.

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The Simple English Wiktionary has a definition for: h.

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