The term "astral" is defined by the Merriam-Webster dictionary as "of, relating to, or coming from the stars" or alternatively as "of or consisting of a supersensible substance held in theosophy to be next above the tangible world in refinement". The word is derived from the late Latin astrālis, or from the Latin astrum, star, and is related to the Greek astron. An "astral body" in that context could refer to a star such as our sun. But in the literature regarding subtle bodies of humans it typically refers to a body composed of a more subtle form of matter that is reported to interpenetrate and reside within the physical body during ones waking hours. Note: since it is our premise that this state of matter is more subtle than the physical matter we're most familiar with we will at this website use the term "subtle body" to refer to this same body also termed elsewhere as the "astral body". The environment this functions in is what we will here call either the "astral plane" or "astral world" or the "subtle world".