Kali comes from the Sanskrit root word Kal which means time. There is nothing that escapes the all-consuming march of time. In Tibetan Buddhism Her counterpart is male with the name Kala. Mother Kali is the most misunderstood of the Hindu goddesses.
"Major Hindu goddess whose iconography, cult, and mythology commonly associate her with death, sexuality, violence, and, paradoxically in some of her later historical appearances, motherly love."
The ferocious image of Mahakali, the goddess of horror, is beautifully carved out of stone. Her each hand is carrying variously a sword, a trishul (trident), a severed head and a bowl or skull-cup (kapala) catching the blood of the severed head. Her eyes are depicted as red with intoxication and in absolute rage, Her hair is shown disheveled, small fangs sometimes protrude out of Her mouth and Her tongue is lolling. She has a garland of human heads. She is shown standing on the prone, inert or dead body of Shiva.
This is interpreted various ways but the most common is that Mahakali represents Shakti, the power of pure Creation in the universe, and Shiva represents pure consciousness, which is inert in and of itself.
Maa Kali wears a garland of skulls and a skirt of dismembered arms because the ego arises out of identification with the body. In truth we are beings of spirit and not flesh. So liberation can only proceed when our attachment to the body ends. Thus the garland and skirt are trophies worn by Her to symbolize having liberated Her children from attachment to the limited body. She holds a sword and a freshly severed head dripping blood.
As the story goes, this represents a great battle in which she destroyed the demon Raktabija. Her black skin represents the womb of the quantum unmanifest from which all of creation arises and into which all of creation will eventually dissolve. She is depicted as standing on Shiva who lays beneath Her with white skin (in contrast to Her black or sometimes dark blue skin). He has a blissful detached look. Shiva represents pure formless awareness sat-chit-ananda (being-consciousness-bliss) while She represents "form" eternally supported by the substratum of pure awareness.
The demon Raktabija gave the fierce Mother Goddess a fair amount of troubles. He possessed a special magical power which allowed him to create new demons from his own blood. Whenever the Goddess wounded him, each drop of blood that spilled to the ground sprouted another demon full of strength and brutality. But in the end the Mother outwitted him. She picked up Raktabija and lifted him high into the air to avoid spilling his blood on the ground, and then, gnashing him between her teeth, she drank his blood and swallowed him whole.
The Gods, who had begun to celebrate victory, became filled with fear. Who was going to stop her? There was only one who could: Shiva, the great God. Besmeared with ashes, the third God of the Hindu Trinity went to the battlefield and lay down motionless among the corpses while the rest of the Gods watched from a safe distance.
The intoxicated Kali staggered across corpses until, suddenly, she found herself standing on top of a beautiful male body - nude and besmeared with white ashes. Awed, she stood still for a moment, looked down at him, and saw straight into the eyes of her husband Shiva. When she realized that she was touching her divine husband with her feet - an unthinkably disrespectful act for a Hindu wife - Kali stretched out her tongue in shame and the destruction came to an end.
Kali is typically shown as a deranged or wrathful half naked woman, and is often depicted dancing upon the corpse of her consort, the god Siva. She is multi-armed; her tongue protrudes; she wears a garland of skulls, holds a severed head in one hand, and brandishes a hooked blade called a kartri, along with other weapons. Yet to most of her devotees, she is a loving Mother, despite her ferocity.
Kali is one of the many forms of Shakti. Maha Kaali is the fiercest of all goddesses of Hinduism.
The light of Shiva formed her face; Yama gave her hair and Vishnu her arms. From the light of Chandra, the moon God, her two breasts were formed. Indra modeled her waist and Varuna her thighs. Earth gave her hips and Brahma gave her feet. The light from the fire God, Agni, fashioned her three eyes. Thus, all gods contributed their power to manifest the auspicious Devi, the great Mother Goddess ("Devi" is derived from the Sanskrit root word "div" which means "to shine" - the Shining One).