Funny thread, especially when the definition of a miniskirt itself is argued. Instead of guessing, why not check Webster?
- a woman's short skirt with the hemline several inches above the knee
Then you can look up "several" and you can see that it means "more than one." So, here is a definition of a miniskirt:
any skirt with more than one inch above the knees. Can this be appropriate? It can be not only appropriate, but very tasteful. The attorney with whom I have worked for years often wears such a skirt (full suit) and it is very professional and looks great. So if done in taste, it can only help. I obviously don't know the circumstances the OP is describing, but it is not hard to surmise that sometimes a female interviewer might not like such a skirt for various reasons and put the interviewee at a disadvantage. I don't know how often that might happen, but it would probably help if you are a down-to-earth and easy-going individual. If you're haughty, then it will not go well regardless of the clothes you wear.
The interview is a sales pitch. If you're there, then you are just as likely to get in as anyone else. Barring any egregious social handicaps, trivial dimensions like your looks and zealousness could be the deciding factor. So wear whatever makes you look
your best.
By the way, you don't have to wear a skirt to look great at all. I know some women who don't have the best legs for a skirt, but the gluteus maximus is absolutely decimus and those professional pants amplify that aspect even further

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