Is the phrase "mean as a dog" an idiom? - briefly
Yes, the phrase "mean as a dog" is considered an idiom in English. It means to be extremely unpleasant or hostile, often used to describe someone's behavior rather than their actual disposition.
Is the phrase "mean as a dog" an idiom? - in detail
The phrase "mean as a dog" is not considered an idiom in the traditional sense. An idiom is a fixed expression that has a figurative, or sometimes literal, meaning. Idioms are language-specific and cannot be understood by simply knowing the meanings of the individual words. For example, "break a leg," "kick the bucket," or "spill the beans" are all idioms whose meanings cannot be inferred from their literal components.
In contrast, "mean as a dog" is a simile, a figure of speech that compares two things using "like" or "as." In this case, it is comparing someone's disposition to that of a dog, suggesting they are aggressive or hostile. The meaning can be understood by anyone familiar with the characteristics of dogs and the word "mean," which in this context refers to being unkind or unpleasant.
While similes like "mean as a dog" may have cultural nuances, they do not possess the same level of figurative complexity as idioms. They are more straightforward comparisons that rely on shared knowledge of the things being compared. Therefore, while "mean as a dog" is a colorful expression, it does not meet the criteria to be classified as an idiom.