Fictitious or nonexistent.
Illusive.
A ghost or apparition.
A placeholder for a pair of players when there are an odd number of pairs playing.
Something apparently seen, heard, or sensed, but having no physical reality; an image that appears only in the mind; an illusion or delusion.
A test object. A test phantom is an object that reproduces the characteristics of human tissue.
Existing or operating without involvement by the body; solely mental or intellectual; “ungrounded”, “heady”.
Not united in a regimented structure; lacking structure and order.
Not expressed or exhibited in material or concrete form; wholly abstract.
Not incorporated into a coherent system; conceptually disconnected.
Incorporeal; not possessed of a body.