Matthew 5:5 (NIV)
Blessed are the meek, for they will inherit the earth.
What does "meek" mean in the original language? Is "meek" a good translation for the original Greek word?
According to this source, the word was used to describe a horse that had been broken-in among other similar usages.
I noticed that none of the current answers explicitly address the question of whether meek is a good English translation. Given the modern connotations of the word meek, it is not a good translation (though it may have been at one time), because in the modern usage it has a sense of craven pandering—the word, at least in my mind, has a derogatory connotation. It's the sort of word I would use of someone whose demeanor is dominated by cowardice and people-pleasing.
However, if meek doesn't carry those connotations for you, it is indeed a good translation. Humble is a possible translation, but because the word often occurs next to another Greek word translated humble, it is often translated gentle instead, which is appropriate.
Two verses which are helpful for understanding the πρα- stem are Galatians 6:1:
which shows the tie between gentleness and not thinking to highly of oneself; and 1 Peter 3:15:
Not that in contrast to people-pleasing, this is fear of God that is enjoined in conjunction with gentleness. As an expanded paraphrase based on the sense of these two verses, I would render the word the gentleness that comes from humility.
It is often noted that the word doesn't require a relinquishing of manliness. While this is certainly true, don't forget that it runs contrary to secular masculine bravado. There is something paradoxical about the character of a godly man in his strength/weakness dialectic. Gentle captures this well.
Matthew 5 has Jesus going up the mountain and chapter 8 has him coming down. These are followed by parallel passages which can be used to illuminate the meaning. The first thing Jesus says is, "Blessed are the poor in spirit." And the first thing Jesus does is heal a leper.
The next parallel is blessed are the meek, and the Centurion asks Jesus to heal his servant.
Just as the leper is an example of one poor in spirit, the Centurion is an example of one who is meek.
Structurally there are three blocks constructed with such parallelisms.
The word praüs is related to 'friend', denoting gentleness and pleasant, the opposite being rough, hard, violent. As an adverb it is used for a quiet and friendly composure which does not become embittered or angry at what is unpleasant. It is not a passive submission, but an active attitude and deliberate acceptance. As such, in the context of Jesus' words, it is one who actively turns the other cheek in a display of confidence in God. redacted from TDNT 6:645.
The Centurion knew the nature of authority, and it gave him the composure to speak with Christ in such a manner, recognizing that Jesus was the authority and being actively confident of a positive response.
Thayer's Lexicon gives the definition of πραΰς as "mildness of disposition, gentleness of spirit, meekness."
Webster's defines meekness as "Softness of temper; mildness; gentleness; forbearance under injuries and provocations....In an evangelical sense, humility; resignation; submission to the divine will, without murmuring or peevishness; opposed to pride, arrogance and refractoriness."
Comparing the two, it seems relatively appropriate, though perhaps different connotations have evolved, making it less than ideal at conveying the thought here.