A friend or ally.

Origin: The word 'मित्र' (mitra) originates from the ancient Sanskrit language, where it was used to denote a friend or ally. It has Proto-Indo-Iranian roots, sharing similarities with the Avestan word 'mithra', which also means friend or covenant.
Historical and Cultural Context: In Vedic texts, 'मित्र' is not only a term for friend but also refers to the deity Mitra, who is associated with the sun and contracts or friendships, emphasizing the sacred bond between friends. Mitra was often invoked in rituals and was considered a guardian of truth and friendship.
Evolution: The concept of 'मित्र' evolved over time, spreading to various cultures and languages. For instance, it influenced the Old Persian 'Mithra', leading to the later Roman Mithraic cult where Mithras was worshipped as a god of light and friendship.
Modern Relevance: Today, 'मित्र' is commonly used in many modern Indian languages to mean friend, retaining its ancient connotations of loyalty and alliance.

In the ancient world, the deity Mitra was often depicted as a figure of unity and harmony, showing the deep cultural significance of friendship in Vedic society.