A term borrowed from India's ancient language, Sanskrit or devanagari (Skt., divine language). Yoni can be translated by several English concepts (origin, source, womb, vulva) and is, to my knowledge, the most respectful word available for naming what in correct language we call vulva (Lat., female genitals, womb) yet which is often (wrongfully) called vagina (Lat., sheath).
The term yoni is the most respectful and beautiful word available for naming what most languages refer to as vulva, pussy, cunt - or by a variety of vulgar equivalents; or with terms that imply shame, for example pudenda.
The term heralds from a culture and religion in which women have long been regarded and honored as the embodiment of divine female energy and where the female genitals are often regarded as the most sacred symbol of the Great Goddess.
Because Tantrics (and many other ancient cultures) worship(ped) the Divine most often in the form of a Goddess, the term yoni has also acquired other, more cosmic meanings, becoming a symbol of the Universal Womb, the Matrix of Generation and Source of All.
In short, the universe really is a yoniverse - hence the name of this website.
Both Christina and myself have published a book about the Yoni, in which She is explored in art and nature, mythology and language:
Christina Camphausen. Yoni Portraits: The Intimate Art of Christina Camphausen.
2009. ISBN 9789081372916
Rufus C. Camphausen. The Yoni: Sacred Symbol of Female Creative Power.
1996. ISBN 0892815620