Old French, Middle French principal (adjective) princely, royal, chief, most important, head of a college (1549) and their etymon classical Latin principālis
- 1: a person who has controlling authority or is in a leading position: as a : a chief or head man or woman
- b : the chief executive officer of an educational institution
- c : one who engages another to act as an agent subject to general control and instruction; specifically : the person from whom an agent's authority derives
- d : the chief or an actual participant in a crime
- e : the person primarily or ultimately liable on a legal obligation
- f : a leading performer : star
- 2: a matter or thing of primary importance: as a (1) : a capital sum earning interest, due as a debt, or used as a fund (2) : the corpus of an estate, portion, devise, or bequest
- b : the construction that gives shape and strength to a roof and is usually one of several trusses; broadly : the most important member of a piece of framing
A head teacher or school principal (also known as headteacher, headmaster, headmistress or the head, sometimes informally in Scots, the heidie or heedie) is the most senior teacher, leader and manager of a school. In the past, the headmaster or headmistress of a British private school was often the owner of the school or a member of the owning family, and the position often remained in the family for many generations.
In Scotland, such officials are sometimes known as the "rector", most commonly in independent schools. In North America, Australia and Ireland (including Northern Ireland), such officials are usually known as the "school principal", but some schools, primarily independent schools, use the term "headmaster" or "head master". As in Scotland, the term "rector" is still in use in the United States in independent, religious schools as by tradition, the Head of School was also a priest. Some American state schools, such as Boston Latin School, Brooklyn Latin School also use the term "headmaster", either because of its history or historical connections.
In Britain, the terms "headmaster" and "headmistress" used to be the official title throughout both state and private schools, with "head teacher" only being used as a term to refer to them collectively. In recent years, however, most state schools have switched to the gender-neutral "head teacher" as the official title. Nevertheless, the gender-specific terms are still in common use, and is still the official title at some of the remaining state grammar schools and most private schools. Some use other terms, such as "high master". Private schools frequently use other titles for officials under the head teacher.
The official term for the third most senior teacher in British state schools and many private schools was "second master" or "second mistress", but these terms have generally gone out of use in the state sector.
Some schools use terms such as "Head of the Upper School" or "Head of the Middle School" to identify those people who are in charge of a particular division of the school, but who are under the direction of the school headmaster.
"Principal" or "Head of School" is used as the title of the head administrator of an elementary school, middle school, or high school in some English-speaking countries, including the United States, India and Australia. Public schools in the United States generally use the title principal whereas private schools in the United States sometimes use the title Head of School. Books and documents relating to the early days of public education in the United States show that the title was originally Principal Teacher.