Boyd’s Bible Dictionary:

(begotten). In plural, the genealogical register (Gen. 2:4; 5:1; Matt. 1:1); family history (Gen. 6:9; 25:12); men of the existing age (Lev. 3:17; Isa. 53:8; Matt. 24:34; Acts 2:40).

Concise Bible Dictionary:

This is used in various senses in scripture.
1. As from a father to his son, or from a king to his successor, γενεά, as in the three series of “fourteen generations” in Matthew 1:17, though the same term is applied where names have been omitted. See GENEALOGY OF THE LORD JESUS.
2. In a much wider sense, as when the Lord said of the unbelieving Jews, “This generation shall not pass away till all these things be fulfilled” (Matt. 24:34; Luke 21:32; compare Deut. 32:5,20). The unbelieving Jews still exist and will until the events take place.
3. As offspring, γέννημα, where there was a moral likeness, as “generation of vipers” (Matt. 3:7).
4. As class, family, etc., γένος. Ye are “a chosen generation” (1 Pet. 2:9).
5. As signifying perpetuity; God’s dominion is “from generation to generation” (Dan. 4:3,34).