(grammar, usually in the plural) Any of the forms of a word which contain its stem(s) in the simplest form, or such a form that, when taken with all the other principal parts, allows the entire paradigm to be derived.

plural of principal part

plural of principal root

(mathematics) A complex number which, when raised to the power of n, yields the radicand of its nth degree radical, and which has the greatest real part among all such numbers, and positive imaginary part in case of equality of the real parts.

plural of vice-principal

An assistant principal or deputy headteacher.

The young male protagonist of a pantomime, traditionally played by a female.

plural of principal boy

plural of principal city

Synonym of central city (“the main city of a metropolitan area; particularly one containing multiple cities”). / Used other than figuratively or idiomatically: see principal, city.