Let us answer this question, base upon God's use of the word generation, and not Webster's definition of the word generation. Why would any teacher of the scriptures step outside of the scriptures and try to give a meaning to certain words use by the Holy Ghost, is beyond me, other than they are trying to deceived men. Peter said: "If any man speak, let him speak as the oracles of God;..." 1 Peter 4:11
When a man speaks on the behalf of God, then they must speak as the oracles of God, not according to the dictionary, which many do, when it come to the word generation. Do men not know that God has hidden his truth within the scriptures of truth? Godly men and women, compare scriptures with scriptures, line upon line, here a little and there a little, to come to the knowledge of truth, trusting the Spirit of God to teach us, using this method that he has given to us to use.
Many interpret the word generation, by their position, or doctrine concerning Matthew 24. Men who believe that Matthew 24 is fulfilled history of 70 A.D. (Historical and Preterit) teach that the word generation to mean: "The whole body of individuals born about the same period; also, the time covered by the lives of these." Of course, this definition come from Oxford and not from the Spirit's definition of the words that he has chosen to use, which we shall consider.
"Thou shalt keep them, O LORD, thou shalt preserve them from THIS GENERATION for ever.:
We ask every reader to read Psalm 12 for themselves and for them to determine the Spirit's use of his words within Psalm 12. The Prophet David knew well what sense he was using the words "this generation"~and so do I, and you will as well, if we both trust the scriptures above men.
If we read through Matthew 24 carefully, then we should not have any problem knowing of whom Christ is speaking about when he use the term~THIS GENERATION. Beginning at verse five down to verse 25, out Lord is speaking about wicked false prophets and those deceived by them! When he said that this generation shall not pass, till all these things be fulfilled; he is referring to a kind of people, that will be here till the very end, and these kind of people will actually increase in numbers as the end approaches.
Generation=the evil and wicked men and women of the devil, whom David said that God has preserved his word from for ever! The word generation in this sense is used by the Holy Ghost many times over in the scriptures: Matthew 23:36~please consider the contents of the context from Matthew 23. Deut. 1:35; Mathew 12:24; Matt. 11:16; Luke 17:25; Matt. 3:7; Proverbs 30:11-14!!