What does theory mean?

A: I. Connotation of theory ?

1, theory, noun. It is a word inherent in the Chinese language, theory refers to people's understanding and discussion of the knowledge of things. ?

2, theory is formed by a number of people (a person often can not) in the long term (years or decades, a year and a half and other short-term can not) with a certain degree of specialized knowledge of the intellectual achievements (sub-field). ?

II. Theoretical near-synonyms: ?

Surface ?

Third, the theory of the antonym : ?

Actual, factual, practical ?