Though a general word, meaning ‘mother,’ it is more often used as a proper noun, as a name of one of the aspects of Pārvatī, the divine spouse of Lord Śiva. Said to be of the colour of water lily, she is depicted with four hands, carrying pāśa (noose), padma (lotus) and pātra (vessel) in three hands whereas the fourth one is exhibiting the abhayamudrā (pose assuring freedom from fear).
Mother Durgā is also sometimes called Ambā.
The first daughter of the king of Kāśī was also named Ambā. Ambikā and Ambālikā were her sisters. Bhīṣma brought the three sisters by force during their svayaṁvara. When he learnt that Ambā had already been betrothed to the king Saubha, he sent her to him. However the king Saubha refused to accept her. She returned and pressed Bhīṣma himself to marry her. He refused her request since he had vowed to remain celibate. Incensed by this, she performed austerities to kill Bhīṣma, was reborn as Śikhaṇḍī (an offspring of Drupada) and ultimately killed him in the Mahābhārata war.