In the English language there ate several synonyms that have come into use for the way people feel as a result of activity or even on the contemplation of activity. They are, for example, fatigue, tiredness, weariness, exhaustion, jadedness, droopiness, and the state of being fagged or flagged. In all of these words a state is being referred to. And, of course, there are the adverbial and adjectival and verbal forms of these words when process is being expressed. When processes are referred to, they generally pertain to processes of restricted parts of the body so that we can say they are subpersonalistic. Customarily, the word psychological is the term used to describe behavior of the organism-as-a-whole. Here again, by some, reference is only to what is experienced and according to custom is also called mental. It would seem that in cases where the term psycl-rological is customarily used, a preferable term would be personalistic. This would include both the mental and the overr. This usage would provide a less biased taxonomy (or classification) of matters to be dealt wich. Body process as such would be srrbpersonalistic. If appropriate vocabularies were set up for the various items of concern, then no one need be confused regarding the class under discussion-the context is certain and one knows which is genus and which is species. This policy has never been consistently carried out, and it is undeniable that confusion or inconsistency reigns. The purpose of the present introductory remarks is two-fold: (a) to introduce the subject of fatigue and (b) in so doing avoid perpetuating the deficiencies just pointed out. For some reason, our of all these words, the noun, fatigue has come to be the most generic, including even the nonbiological systems and substances outside the body. Since the word fatigue was first used to describe the human condition, it would seem reasonable that psychology, the discipline which defines itself as the science of the behavior of humans, would restrict the term fatigue to describing the state of the human organism as a person, rather than to describing the function or condition of parts of it as such. Unfortunately, this policy has not been followed. All this means that a great deal of variance exists in what is actually meant when the word fatigue is used. Some workers in the area have called for a clarification, supposing that some agreement in terminology on a rational basis could eventuate. Surely it is nor too much to expect this, because the optimal progress of human understanding in general and in science in particular is dependent upon the adoption of clear means of verbal communication. A revision and sharpening of vocabulary would not restrict research nor build science in some partisan way. Bartley and Chute (1947) have suggested that the term fatigue be used to label the class of phenomena that we call human feelings and self-evaluations.