In the United States, a youth organization administered by the Cooperative Extension System of the United States Department of Agriculture with the mission of "engaging youth to reach their fullest potential while advancing the field of youth development."

(slang, street name) The drug heroin.

Water as a chemical substance. / (Malaysia, Internet slang, humorous, politics) Hishammuddin Hussein Onn, Malaysian politician and son of Hussein Onn, third prime minister of Malaysia.

(slang) A hydrogen bomb.

(figuratively) The hour at which any major event planned for the future is set to begin, as used in United States military.

(euphemistic) The word hell/Hell. / (humorous) Any word beginning with h that is not normally taboo but is considered to be so in the given context, such as horny.

(fandom slang) The ship of characters Harry Potter and Hermione Granger of the Harry Potter series.

(Judaism) b'ezrat hashem (Transliterated form of ב״ה, written at the top of documents). / (Judaism) baruch Hashem

(mining) The part of a plunger pump that contains the valve.

(astronomy) Fe/H (metallicity)