estiv-, aestiv-; estuar-, aestuar-
(Latin: pertaining to summer; heat, fire; the ebb and flow of the sea, tide)
2. A heaving or undulating motion: "There was an estus of the earth when a mild quake happened."
2. Relating to or happening during summer.
2. In zoology, to spend the summer in a dormant or an inactive and torpid (suspended animation) condition: Alex was amazed to realize that many animals tend to estivate during the summer; especially, during the hot dry weather.
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During estrus, the animal is said to be "in heat".
This word is presented here to let you know that it has no etymological connection with the estiv-, aestiv-; estuar-, aestuar- elements of this unit. Most dictionaries do not make this distinction and that is why it is presented here.2. Etymology: from Latin oestrus, "frenzy, gadfly"; from Greek oistros, "gadfly, breeze, sting, mad impulse; frenzy".
2. A descriptive term relating to or found in the arms of the seas that extend inland to meet the mouths of rivers.
2. The tidal mouth of a great river, where the tide meets the current of fresh water.
3. A semi-enclosed coastal body of water that has a connection with the open sea and within which fresh water and salt water mix by means of currents and tides.
4. Etymology: from Latin aesturium, "a tide place" from aestus, "boiling heat, fire; the ebb and flow of the sea, tide"; related to aestus, "heat".
An estuary is the mouth of a river where the tide of the ocean and the current of the river meet, and the rough waters at such a point demanded a word of action. The Latin aestuarium gave us the word from aestus which meant "heat, bubbling, boiling" and so the "swelling sea".
There are those who are trying to develop the tidal energy of the estuaries; that is, water-powered turbines that spin in the current as the tides come and go, turning generators to make electricity that is lean and, they hope, reasonably priced.
Estuaries make promising locations for tidal power if the technology improves and more power can be generated in slower currents.