The meaning depends on the usage. 这两人的脾气是截然相反的。 These two people were diametrically opposed in temperament (脾气）.

脾气 temper 脾气这个词从广泛应用的角度来说的话，就是只的一个人的性格。 举几个例子： 1.脾气好：be courteous and accessible. 2.脾气坏：bad temper . 其实很好理解，就是容易接近的人就nice temper 不容易接近的就是bad temper The word temper from the widely used temper temper standpoint, is one of the character, but also refers to the incomplete character. Some examples: 1.脾气好：be courteous and accessible. 2.脾气坏：bad temper . In fact, very good understanding, is easy to close to the people on the temper nice is not easy to close to the temper bad

Actually, the answers by "heart" and "Jorge Rodriguez" are pretty good. I just want to add another example. 你不要总是发脾气了。 Here 发脾气 means "losing control" or "get angry".

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