APA Dictionary of Psychology

a statistical hypothesis that is not specific about all relevant features of a population or that does not give a single value for a characteristic of a population but allows for a range of acceptable values. For example, a statement that the average age of employees in academia exceeds 50 is a composite hypothesis, as there are a variety of ages above that number that the average could assume to validate the statement. Alternatively, a composite hypothesis could give a specific value for one characteristic (e.g., the mean) but not others (e.g., the variance). Compare simple hypothesis.