Easton's Bible Dictionary
Genesis 2:4, "These are the generations," means the "history." 5:1, "The book of the generations," means a family register, or history of Adam. 37:2, "The generations of Jacob" = the history of Jacob and his descendants. 7:1, "In this generation" = in this age. Psalm 49:19, "The generation of his fathers" = the dwelling of his fathers, i.e., the grave. Psalm 73:15, "The generation of thy children" = the contemporary race. Isaiah 53:8, "Who shall declare his generation?" = His manner of life who shall declare? or rather = His race, posterity, shall be so numerous that no one shall be able to declare it.
In Matthew 1:17, the word means a succession or series of persons from the same stock. Matthew 3:7, "Generation of vipers" = brood of vipers. 24:34, "This generation" = the persons then living contemporary with Christ. 1 Peter 2:9, "A chosen generation" = a chosen people.
The Hebrews seem to have reckoned time by the generation. In the time of Abraham a generation was an hundred years, thus: Genesis 15:16, "In the fourth generation" = in four hundred years (Comp. verse 13 and Exodus 12:40). In Deuteronomy 1:35 and 2:14 a generation is a period of thirty-eight years.
Noah Webster's New International Dictionary of the English Language
1. (n.) The act of generating or begetting; procreation, as of animals.
2. (n.) Origination by some process, mathematical, chemical, or vital; production; formation; as, the generation of sounds, of gases, of curves, etc.
3. (n.) That which is generated or brought forth; progeny; offspring.
4. (n.) A single step or stage in the succession of natural descent; a rank or remove in genealogy. Hence: The body of those who are of the same genealogical rank or remove from an ancestor; the mass of beings living at one period; also, the average lifetime of man, or the ordinary period of time at which one rank follows another, or father is succeeded by child, usually assumed to be one third of a century; an age.
5. (n.) Race; kind; family; breed; stock.
6. (n.) The formation or production of any geometrical magnitude, as a line, a surface, a solid, by the motion, in accordance with a mathematical law, of a point or a magnitude; as, the generation of a line or curve by the motion of a point, of a surface by a line, a sphere by a semicircle, etc.
7. (n.) The aggregate of the functions and phenomena which attend reproduction.