I was taught that Christian women can not cut their hair, that uncut hair is the covering that Paul was talking about in 1Cor 11:2-16 and that if they trimmed it (even breaking a split end off) they were no longer covered. While I agree that long hair seems to be the covering, I do not agree that it has to be uncut hair. The meaning of the word translated "long hair" is simple and uncut is not part of it.
This is what I was taught as a teenager: In 1 Cor 11:2-16 Paul teachers that women have to have their heads covered with something when they pray or prophecy. Until verse 15 he does not say what the covering is; it could be a natural covering or a veil. Some people believe it has to be a veil over their hair because they feel that word "covering" can only mean an artificial covering. I don't think the word demands that, but that is a topic for another day. In verse 16 Paul finally says that "...long hair is given to her as a covering." So, we know that women are to have their head covered by long hair
Hair comes in all lengths. Some women naturally can grow their hair to their knees while others can hardy grow it to their shoulders. This lack of precision bothers some people, so they say that it has to be uncut hair, that way we don't have to worry about how long a women's hair has to be to be called "long." They have two lines of reasoning to prove this. One is the meaning of the word translated "long hair."
Here are the definitions for komaow from the lexicons that I own:
Thayer "to let the hair grow, have long hair"
Bauer "wear long hair, let one's hair grow long"
Liddell and Scott "to let the hair grow long, wear long hair"
Moulton "to have long hair, wear the hair long"
Zonhiates "to let the hair grow long, wear long hair"
No one defines the word as uncut. That is an interpretation of Thayer's definition "to let the hair grow." It is felt that if you trim your hair you aren't letting it grow and it isn't long. However, the meaning of the word is clear: women are to let their hair grow to a length that is long and to wear it that way. The idea that it has to be uncut is not part of the meaning of this word. As for the problem that we can't define how long "long" is, that is rubbish. Nobody believes that a man can grow his hair past his shoulders as long as he trims it (if you trim it it will not be uncut and therefore not "long"). Paul said "Does not the very nature of things teach you that if a man has long hair, it is a disgrace to him..." (1Cor11:14). We can by nature recognize what long hair is, my mother and wife never have a problem knowing when my hair is too long and I need a hair cut.
The other line of reasoning is the Nazirite vow. Nazirites were to leave their hair uncut for the period of their vow. There are a lot of problems with using this vow as proof that women are not to cut their hair. First, Paul never refers to it. Wouldn't it have been an excellent illustration of what he meant by long if he had referred to this vow and said women were to leave their hair uncut like the Nazirites did? Strikingly he didn't bring it up. The reason might be that he did not want them to leave their hair uncut. Second, Paul took a Nazirite vow (Acts 18:18). Since he left his hair uncut for a period of time did he have long hair? Or did he just let it grow to certain length and cut it before it got "long?" Paul didn't use the Nazirite vow in this passage, and we shouldn't either.
What we know for certain is that long hair is given to women as a covering, and they are to grow it to a length that is long and wear it that way. When we introduce the idea of uncut to this passage we are bring in something that is not there. No one defines it as uncut and there are no translations that translates it that way.