H - History, Hydro-, Horoscope, Hero.

History. From Ancient Greek ἱστορία, historia, learning through research, narration of what is learned. From ἱστορέω, historeō, to learn through research, to inquire. From ἵστωρ, histōr, the one who knows, the expert.

Derived or related words: historian, historic, historically, prehistory, historiography etc.
 

 

Hydr(o)-. From Ancient Greek ὑδρο-, hydro-, from ὕδωρ, hydor, water. Consequently, all words with hydr(o)- as a prefix are Greek. 

Derived or related words: hydrogen (from hydro- and γεννάω, gennaō, I bring forth, to life), hydrate/hydration (to take up, consume or become linked to water/the process of providing an adequate amount of water to body tissues), hydroelectric (from hydro- and electric, something that generates electricity by converting the energy of moving water), hydrodynamic (from hydro- and dynamic, operated by the force of water in motion), hydroxide (from hydro- and oxide, an univalent anion (OH^-1) based on the hydroxyl functional group, hydrolysis (from hydro- and lysis, a chemical process of decomposition involving the splitting of a bond and the addition of the hydrogen cation and the hydroxide anion of water).

Horoscope. From Ancient Greek ὡροσκόπος, hōroskopos. From ὥρα, hōra, hour and σκοπός, skopos, watcher. The position of the planets and stars at the moment of someone's birth; a diagram of such positions.

Hero. From Ancient Greek ἥρως, hērōs, demi-god. A real or mythical person of great bravery who carries out extraordinary deeds. 

Derived or related words: heroic, heroism, heroin, heroically.