What is ...
... a psychologist?
A university graduate who has studied psychology. Psychologists deal with describing, explaining, predicting and changing human thoughts, feelings and behaviours. Only those holding a university degree in psychology are entitled to use the professional title "psychologist".
Extract from: Homepage of the German Association of Psychologists
... social psychology?
Social psychology is an empirical science that examines human thoughts, feelings and behaviours in social situations.
Greitemeyer (2012): Sozialpsychologie
... the scientific study of the way in which people's thoughts, feelings and behaviours are influenced by the real or imagined presence of other people.
Allport (1985): The historical background of social psychology
... the psychology of health?
... is the science of human thoughts, feelings and behaviours in the context of health and disease.
Renneberg & Hammelstein (2006): Gesundheitspsychologie
... work psychology?
The central topic is the psychological study and change of human work.
Dorsch (1998), Psychologisches Wörterbuch
... organisational psychology?
... refers to the interactions between several individuals in organisations (examples: industrial companies, authorities, schools, hospitals, prisons, clubs).
[Topics of organisational psychology:] promotion of teamwork ... co-operative leadership style ... work satisfaction and motivation ... staff selection, performance reviews ... staff development ... organisational development, climate and culture ...
Dorsch (1998), Psychologisches Wörterbuch
... a psychotherapist?
A psychotherapist practises psychotherapy. He may be a psychologist ("psychological psychotherapist"), or a physician ("medical psychotherapist") ... [who,] in addition to his "basic profession", has completed advanced training as a psychotherapist. ... Psychotherapy literally means treatment of the mind (the psyche) or of psychological problems. It provides help for mental, emotional and behavioural disorders such as anxieties, depressions, eating disorders, child and adolescent behavioural disorders, addictions and obsessions.
Furthermore, psychotherapy is applied to psychosomatic disorders. The term psychosomatics conveys the idea that the psyche (mind) has an adverse effect on the soma (body). Psychological treatments are used more and more in support of medical treatments and for organic disorders (e.g. for chronic diseases, severe pain, neurological disorders, cardiovascular diseases).
Extract from: Homepage of the German Association of Psychologists
... a psychiatrist?
Specialist physician for psychological diseases and disorders. Psychiatrists approach psychological problems from the physical side. A psychiatrist has studied medicine. During his studies he mainly focused on the functioning and the diseases of the human body - and barely at all with the human psyche - and learnt to treat these diseases primarily with medication. After his studies in medicine he completed several years' training as a psychiatrist in medical institutions. During this training he acquired special expertise on the origin and course of diseases of the mind and soul, and learnt how to diagnose them and to treat them, mostly with medication, the so-called psychoactive drugs.
Extract from: Homepage of the German Association of Psychologists