These words refer to the characteristic ways that people reveal themselves in their actions. Behaviour is the most general of these; at its most technical, it refers to all activity of people, singly or collectively, that might be studied by psychologists, sociologists or anthropologists: paranoid behaviour ; peer-group behaviour in preschool children; mating behaviour in New Guinea. In everyday use, the word more frequently refers to positive or negative social activity: promising to be on my best behaviour ; such incredibly rude behaviour . Conduct can also refer to individual or group activity, but in a less technical sense than behaviour ; it also may be categorized positively or negatively. It does suggest a narrower range of activity than behaviour , implying the breaking or following of prescribed rules: a bad-conduct discharge from the army; a prison sentence commuted for good conduct . The word is distinct from these other words because it may suggest an ethical or moral basis for measuring behaviour : conduct befitting an honest man.

Manners refers not so much to adherence to ethical standards as to the arbitrary forms by which a social group has traditionally acted. Here a positive or negative evaluation may depend on subjective taste as much as anything else: the vulgar manners of the nouveau riche; the easy, natural manners that were second nature to her. The word most often refers to individuals, but can sometimes apply collectively to a whole social group: the affected manners of our debased age.

Deportment is a more formal synonym for conduct , but the set of rules that measure deportment may be arbitrary choices to facilitate a goal or may be superimposed from above, instigated especially to instil a respect for authority. It refers also to manner of bearing, carriage and address as well as to general conduct . A common use is to describe the behaviour of pupils in school: sending home remarks critical of his uncooperative deportment ; measures to improve the deportment of her class. Demeanour is distinct from all these words in that it almost exclusively refers to the way a particular person acts at a particular time, and suggests an assessment of the person’s dress, bearing, attitude and expression: a habitually quiet man who had never shown such an agitated demeanour : a supervisor known for her invariably soft-spoken and relaxed demeanour .