The article presents results of empiric sociological research which had the aim to identify the cognitive aspects of a person’s loneliness. Analysis of the messages from one Internet forum made it possible to define the notional borders of loneliness understanding by those who have this feeling. On the basis of received material the author made a classification of the messages according to following aspects – number of responses, context of reasoning, borders of social distance, level of involvement into the discourse of responses’ authors. As a result, it was found that loneliness, long absence of understanding and relation with soulmates, is interpreted as a social deviation. On the contrary, short-term physical loneliness in spatial context is interpreted as normal routine of a reflecting person.