Delta is the name of the fourth letter of the Greek alphabet (Δ, δ), equivalent to the Latin "D, d". It was derived from the Phoenician letter “daleth”, “the door”.
We call also "delta" the mouth of some rivers, because the precipitation of sediments transported by various arms make precisely a triangular shaped landform. In antiquity the most famous delta is this of the Nile River, about which Herodotus (lived between 484-425) speaks repeatedly, for example in his book II considering it a alluvial product.
Herodotus is the author of the famous phrase "(Egypt) is a gift of the Nile; δῶρον τοῦ ποταμοῦ (Histories, II, 5.1)”
The old gégografos as Strabo or Pomponius Mela refer to this mouth as "The Delta". Later the name has been widely used as a technical term in river geography.
Delta is also the modern instrument triangular shaped wing (delta wing, hang gliding) that allows some people to realize the old intrepid human desire to fly like Daedalus. The characteristics of the materials, lighter and stronger, allowing these people to ascend to great heights, move to distant places taking advantage of the air currents, sustained for hours in the air and land with the necessary finesse to avoid (not always) accidents.
"Deltoid" is called man shoulder muscle precisely because it is shaped like the Greek letter.
As mathematical symbol the letter δ is used to indicate the change of a function with respect to one of the variables that describe the function itself. Δ is also commonly used in Physics to represent the Dirac delta function.
The uppercase Δ represents the Laplacian operator introduced by Laplace in his study of partial differential equations.
Both uppercase and lowercase letter delta Δ, δ plays an important role in describing important Physical theories as the equations of Maxwell’s electromagnetism , the wave equation of quantum mechanics or gravitation theory of Einstein.
The lowercase letter delta δ is used in Astronomy to indicate the position, along with the letter alpha α, of the stars in the sky. Two angles are needed (right ascension and declination) to define the position of the stars and other objects in the sky. The right ascension is denoted by alpha and delta declination (both lowercase).
Delta is also the euphemistic name with which the Greeks referred to female genitals, the pubic triangle that in adolescence is covered with hair. Later they used the name " mons Veneris = Hill of Venus" and "mons pubis = pubic bush" to designate the same part of the female body.
For example, in the comedy of Aristophanes Lysistrata, 151 "the convincing Greek wife" says:
By the two Goddesses, now can't you see
All we have to do is idly sit indoors
With smooth roses powdered on our cheeks,
Our bodies burning naked through the folds
Of shining Amorgos' silk, and meet the men
With our dear Venus-plats plucked trim and neat.
Their stirring love will rise up furiously,
They'll beg our arms to open. That's our time!
We'll disregard their knocking, beat them off—
And they will soon be rabid for a Peace.
I'm sure of it. (Jack Lindsay, Ed. )
Πολύ γε νὴ τὼ θεώ.
Εἰ γὰρ καθῄμεθ᾿ ἔνδον ἐντετριμμέναι,
Κὰν τοῖς χιτωνίοισι τοῖς᾿Αμοργίονις
γυμναὶ παρίοιμεν δέλτα παρατετιλμέναι,
στύοιντο δ᾿ἄνδρες κἀπιθυμοῖεν σπλεκοῦν,
ἡμεῖς δὲ μὴ προσιείμεθ᾿, ἀλλ᾿ ἀπεχοίμεθα,
σπονδὰς ποήσαιντ᾿ ἂν ταχέως, εὖ οἶδ᾿ ὅτι.
Let us remember that in this comedy, Greek wives, so sick of war that occupies their husbands, have declared a "sex strike" to force them to make peace. See: http://en.antiquitatem.com/lysistrata-aristophanes-sex-strike
It is known that in relation to the "mountains" are two trends or actions: one more conservative and ecological which means allowing the forest to its free and natural development and a more interventionist and culturally which means to retouch and make amends to the nature. For those who think that fashion or custom of depilatory the mount, that has taken hold today, is something new and extraordinary, I advise you to observe the many representations that appear on Greek vases or reread the above quote from Lysistrata.
Perhaps mixing the two names "Delta" and "Mount of Venus" writer Anais Nin wrote a famous pornographic work (Greek πόρνη, Porne, "prostitute" and γράφειν, graphein, "to record, write, illustrate) that titled" The Delta of Venus ".