Overview
Big (大きい) is used when the, or a, subject of the work is of above average size, unless it's average size for something that is big by default, in which case the tag would be used for an average sized subject. If it is above average size for something that is small by default, that would make it average size, therefore the tag would not be applicable.
The word may be used in conjunction with other words (for example, "onions") to create what is called a "noun phrase" in syntax ie the subject of the sentence (for example, pairing it with the word, "onions", to create the term, "big onions") though these would amount to entirely different tags whose use will not be covered in this article.
If unsure whether to tag your work with, "big," ask yourself: Is it big? "Big" refers to a subject of above average size, you may recall. If your answer to this question is a resounding "no," it may be prudent to choose a different tag that more accurately describes the situation, such as "medium," or, "small".
