An avatāra is a descent of the divine into the world. Viṣṇu is said to take forms, traditionally ten, among them Rāma and Kṛṣṇa, whenever dharma declines. The Bhagavad Gītā gives the classic statement of the idea. Devotional traditions treat the avatāras as fully divine.
Avatāra
Descent: a form in which God, especially Viṣṇu, comes into the world to restore dharma.
Also: Avatar