Definition of theorem in English:
theorem
Syllabification: the·o·remPronunciation: /ˈTHēərəm, ˈTHi(ə)r
/
noun
Physics & Mathematics 1A general proposition not selfevident but proved by a chain of reasoning; a truth established by means of accepted truths.More example sentences
 Ideally the definitions would generate all the concepts from clear and distinct ideas, and the proofs would generate all the theorems from selfevident truths.
 There is a theorem proved by Kurt Godel in 1931, which is the Incompleteness Theorem for mathematics.
 In modern Fourier analysis, theorems are usually less important than the techniques developed to prove them.
 1.1A rule in algebra or other branches of mathematics expressed by symbols or formulae.More example sentences
 But why would you pass up free education that could take you places somewhere someday, even though we will never use the algebra theorems ever?
 We learn how the dynamics of addition and subtraction are linked to multiplication and division, and eventually to theorems of algebra.
 He also used letters to replace numbers and was able to state general algebraic theorems but this early use of algebraic notation was not used by subsequent writers.
Derivatives

theorematic
 More example sentences
 The ideas we present are basically in the nature of ‘throwaways,’ suggesting topics where more sophisticated analyses and clear theorematic results would be desirable.
 To read it selectively according to particular topical or theorematic segments is to break the allimportant systematic links that bind the treatise into an extraordinarily elegant whole.
 This being the case, I limit my comments in this review to the few immediately understandable sentences or paragraphs written in English (i.e., the side comments, not theorematic material) that a few of the authors have seen fit to include.
Pronunciation: /ˌTHēərəˈmatik, ˌTHi(ə)rə/
adjective
Origin
mid 16th century: from French théorème, or via late Latin from Greek theōrēma 'speculation, proposition', from theōrein 'look at', from theōros 'spectator'.
More definitions of theorem
Definition of theorem in: The British & World English dictionary
 The English Synonyms