Noun
(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.
Holonyms: declension, conjugation
(mathematics) A polynomial approximation of a power series, made up of monomials whose indices lie in the Newton diagram of the power series and which occur with the same coefficients as in the original power series.
(mathematics) The portion of a Laurent series that has negative exponents.
Used other than figuratively or idiomatically: see principal, part.
Source: en.wiktionary.orgThose who make their dress a principal part of themselves, will, in general, become of no more value than their dress. William Hazlitt
To love truth for truth's sake is the principal part of human perfection in this world, and the seed-plot of all other virtues. John Locke
The man who occupies the first place seldom plays the principal part. Johann Wolfgang von Goethe
Let not judges also be ignorant of their own right, as to think there is not left to them, as a principal part of their office, a wise use and application of laws. Francis Bacon
Misery, mutilation, destruction, terror, starvation and death characterize the process of war and form a principal part of the product. Lewis Mumford