The term 'phantasy' may be used by psychoanalysts to mean an imaginative fulfillment of frustrated wishes, conscious or unconscious. This approximately condenses what is generally seen as Freud's main use of the term. It may also be used, inter alia, to denote the primary content of unconscious mental processes, as the mental representative and corollary of instinctual urges, and as based on or identical with Freud's postulated 'hallucinatory wish-fulfillment' and his 'primary introjection', which reflects Melanie Klein's extension of Freud's concept. The differences between the two notions were first clearly aired during the Controversial Discussions conducted by the British Psycho-Analytical Society during the war. This paper gives a necessarily abbreviated and incomplete account of some of the points made then, to give some detail of how widely the two notions differed. It then notes how the term 'phantasy' is still used for such widely differing notions: to indicate the problems that must exist, of what we mean and of how to communicate our ideas, if different people mean such different things by one technical term that is in constant use.