Haykal is a loan word from the Hebrew word hēyḵāl which means temple and specifically Solomon's Temple in Jerusalem. In Arabic, the word also means the body or form of something, particularly the human body. In the Bahá'í tradition, the haykal was established by the Báb — the person who told of Bahá'u'lláh's coming — who represented the haykal as a five-pointed star representing the human body as a head, two hands, and two feet. The Báb wrote many letters, tablets, prayers and more in the shape of a five-pointed star, including some that included many derivatives of the word Bahá’ (see below).

In Bahá'u'lláh's writings, specifically the Súriy-i-Haykal (Tablet of the Temple), while the meaning of temple remains present, the haykal is used mainly to mean the human body, but particularly the body of the Manifestation of God — a messenger from God — and the person of Bahá'u'lláh himself. In the Tablet, the haykal is also used to refer the word of God, which is revealed by the Manifestations of God.