American Heritage® Dictionary of the English Language, Fourth Edition
- n. A constellation in the Southern Hemisphere near Tucana and Mensa.
Century Dictionary and Cyclopedia
- n. A southern constellation introduced in the sixteenth century. It lies south of Eridanus, Horologium, and Reticulum, and contains three stars of the third magnitude.
- n. A genus of venomous sea-snakes, type of family Hydridæ: now disused, the genus being termed Hydrophis, and the family Hydrophidæ.
- n. [lowercase] Some fabulous or undetermined water-snake.
- n. astronomy A winter constellation of the southern sky, said to resemble a small serpent. It lies between the constellations Mensa and Tucana. It is not to be confused with the constellation Hydra.
GNU Webster's 1913
- n. (Astron.) A constellation of the southern hemisphere, near the south pole.
- n. a constellation in the southern hemisphere near the south celestial pole
- Named by Dutch explorers Pieter Dirkszoon Keyser and Frederick de Houtman between 1595 and 1597. From Latin hydrus, a "water serpent", originally from Ancient Greek Ύδρα (Hydra) (Wiktionary)
- Latin, from Greek hudros, water snake; see wed-1 in Indo-European roots. (American Heritage® Dictionary of the English Language, Fourth Edition)
“Magnetar wanted to name the CDO after a small constellation in the southern sky called Hydrus, which means "male water snake.”
“( "Hydrus," not "Hydra" - Hydra is six R.A. hours over and farther north.)”
Time For The Stars
“A planning submission was expected to be sent to West Berkshire Council at the end of May for the new "Hydrus" hydro-dynamics building.”
“West Berkshire Council has confirmed that its Eastern Area Planning Committee will consider the planning application for Project Hydrus at a meeting on Wednesday.”
“The release of the logs comes as the local council is expected to give planning approval this week for Project Hydrus, the next generation of thermonuclear warheads that will cost hundreds of millions of pounds to develop.”
“Argo-Navis, and joined the chase against the starry Cetus far beyond the utmost stretch of Hydrus and the Flying Fish.”
“And below this gulf the first town is Dryus,  which is now called Hydrus.”
“Dryus, city in southern Italy, called also Hydrus, V. xv.”
“Looking back, we saw, low down, parts of the Phoenix and the Crane; higher up, the Toucan, Hydrus, and Pavo.”
“And beneath the effulgent Antarctic skies I have boarded the Argo-Navis, and joined the chase against the starry Cetus far beyond the utmost stretch of Hydrus and the Flying Fish.”
These user-created lists contain the word ‘Hydrus’.
A list of words that are odd or words that I have looked up.
Inspired by a Twitter exchange between Kory Stamper and other lexicographers about mythical beings with "fabulous" in their definitions.
The International Astronomical Union (IAU) recognizes 88 official constellations.
Looking for tweets for Hydrus.