Psa 86:1 A Prayer of David. Bow down Your ear, O Jehovah, hear me; for I am poor and needy.
Psa 86:2 Preserve my soul; for I am holy; O You my God, save Your servant who trusts in You.
The word, in this case, was holy- what did David mean by it? Well, I fell into a word study on 'holy' and found that there are 6 Hebrew words translated thus in the Old Testament, and four in the new. I want to start with the lesser points before I get to the bigger picture.
The majority of these words stem from the Hebrew qadash- meaning to be or to make clean. The prime example of this specific word comes in its very first use, in Exodus 30:8, saying that the sabbath shall be kept holy. All but one of the Hebrew words are derived from this one in some way. The most used version- in fact, the very first version used- is the word qodesh, referring to a place or more usually to an item that is sacred- for example, in that first use, Exodus 3:5, the Holy ground at the burning bush where Moses was told to remove his sandals.
A place that is more formally consecrated might be indicated by the word miqdash, which is first used in Psalms 68 describing "the holy places". Examples given in my concordance include a chapel or a palace- or, perhaps, a temple.
Now the NT words are an interesting story. All but 9 of the many places holy is used in the NT are from the word hagios, which the concordance notes carries the concept of being purified from defect. Twice, the word hieros is used- in 1 Corinthians 9:13 and 2 Timothy 3:15- both times denoting items that have been formally consecrated- which makes it basically the same as the Hebrew qodesh. One word- hagiazo, which as you might guess comes from hagios, is used only once- in Revelations:
Rev 22:11 He acting unjustly, let him still act unjustly. And the filthy, let him be filthy still. And the righteous, let him be righteous still. And the holy, let him be holy still.
This denotes someone who HAS been sanctified or purified.
But now that leaves us two more concepts- the most important ones- to look at. One of them is the concept of a personal, like God holiness- captured by the Hebrew word qadowsh and the Greek hosios- for which the description under the Greek nails it best: to be right by divine character, as opposed to human means or formal consecration. In other words Holiness that means you are walking in the character of God.
The other is encapsulated in the Hebrew word that David used in our opening verse, chaciyd. This connotes being pious, kind, or godly. In other words, being the kind of person that would make others say, "That feller's a real saint." But take it one step farther. Chaciyd derives from the word chacad, a word that had a very telling description: to bow the neck, as a courtesy to an equal. Get that? That is the whole concept of considering others greater than oneself.
So, what is being holy? When you look at these main two definitions- divine character and deference to others- you can see it was the same question that was asked of Jesus in Matthew 22:
35 Then one of them, which was a lawyer, asked him a question, tempting him, and saying,
36 Master, which is the great commandment in the law?
37 Jesus said unto him, Thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy mind.
38 This is the first and great commandment.
39 And the second is like unto it, Thou shalt love thy neighbour as thyself.
40 On these two commandments hang all the law and the prophets.
And THAT is what it means to be holy.