In Egyptian mythology, ba (CR:24) (LH:5) (TL:29), hieroglyph: , refers to the soul of a person or god; one of the eight parts of the "human" according to the Egyptian model. The ba gets weighted on the "Scale of Maat", in the Judgment Hall, against the "feather of truth", to determine if one goes to the kingdom of Osiris, or the fire pit of Ammit.
The ba, in the Egyptian human model, is closely related to the a term closely related to the "ka", aka spirit, and "ab", aka heart.
The following are quotes:
- “Ba: the soul, or that part of a person that had eternal existence after death. The Ba, closely associated with the Ka (each person's double) and the Ab, or heart, was one of the principal elements of the life in man. The Ba amulet was in the form of a man-headed hawk wearing a beard. After death, the Ba was believed to visit its body in the tomb. Many graves had narrow passages in the pits so that the Ba might find its way there. In the Pyramids of Me roe, openings were left in the stone coverings near the apex so that the Ba might enter them, and a ledge to stand on was placed beneath each opening. In the Book of the Dead the Ba is seen visiting its body, to which it presents the symbol shen, symbolic of eternal life. The final union of all souls with their bodies was believed to take place in the heavenly Anu Heliopolis. Small figures of the Ba made of gold and inlaid with semiprecious stones were placed on the breast of the mummy in the hope of preserving it from decay.”
- — Anthony Mercante (1978), Who’s Who in Egyptian Mythology (ka, pg. 81; ba, pg. 19)
- “As their lives and loves survive in memory among their offspring, their ka souls will continue to shine from the shadow play among the ba structures of this book.”
- — Karl Luckert (1991), “In Memory” of father Wilhelm G. Luckert, whose “restless mind harbored questions and doubts which the Karl imbibed in childhood”, and mother Emilie Luckert-Hilt, who passed while book was going to press; note: he seems to have “ka” incorrectly associated with soul, whereas correctly the “ba” is typically translated as soul 
- Mercante, Anthony S. (1978). Who’s Who in Egyptian Mythology (editor and reviser: Robert Bianchi) (ka, pg. 81; ba, pg. 19). Metro Books, 1995.
- Luckhert, Karl. (1991). Egyptian Light and Hebrew Fire: Theological and Philosophical Roots of Christendom in Evolutionary Perspective (pg. viii). SUNY Press.
- Ba – Hmolpedia 2020.