Colleagues are those explicitly united in a common purpose and respecting each other's abilities to work toward that purpose. A colleague is an associate in a profession or in a civil office.
Thus, the word collegiality can connote respect for another's commitment to the common purpose and ability to work toward it. In a narrower sense, members of the faculty of a university or college are each other's colleagues; very often the word is taken to mean that. Sometimes colleague is taken to mean a fellow member of the same profession. The word college is sometimes construed broadly to mean a group of colleagues united in a common purpose, and used in proper names, such as Electoral College or College of Cardinals.
Sociologists of organizations use the word collegiality in a technical sense, to create a contrast with the concept of bureaucracy. Authors such as Max Weber consider collegiality as an organizational device used by autocrats to prevent experts and professionals from challenging monocratic and sometimes arbitrary powers. More recently, authors such as Eliot Freidson (USA), Malcolm Waters (Australia) and Emmanuel Lazega (France) have shown that collegiality can now be understood as a full fledged organizational form. This is especially useful to account for coordination in knowledge intensive organizations in which interdependent members jointly perform non routine tasks -an increasingly frequent form of coordination in knowledge economies. A specific social discipline comes attached to this organizational form, a discipline described in terms of niche seeking, status competition, lateral control, and power among peers in corporate law partnerships, in dioceses, in scientific laboratories, etc. This view of collegiality is obviously very different from the ideology of collegiality stressing mainly trust and sharing in the collegium.
In the Roman Republic, collegiality was the practice of having at least two people, and always an even number, in each magistrate position of the Roman Senate. Reasons were to divide power and responsibilities among several people, both to prevent the rise of another king and to ensure more productive magistrates. Examples of Roman collegiality include the two consuls and censors; six praetors; eight quaestors; four aediles; ten tribunes and decemviri, etc.
There were several notable exceptions: the prestigious, but largely ceremonial (and lacking imperium) positions of pontifex maximus and princeps senatus held one person each; the extraordinary magistrates of Dictator and Magister Equitum were also one person each; and there were three triumviri.