Genea (γενεά) refers to a generation — the totality of people alive at a given time, sharing common characteristics of birth, historical experience, or moral disposition. It can also refer to a genealogical lineage or the period of approximately 30-40 years. Jesus frequently used this term to describe the people of His day, often negatively.
Jesus called His generation "evil and adulterous," "faithless and perverse," "wicked" — because they had seen unprecedented revelation (including the Son of God Himself) and rejected it. The phrase "this generation will not pass away" (Matthew 24:34) is exegetically significant, understood variously as referring to the generation of 70 AD or to the Jewish people as an ongoing ethnic group. Regardless, the call is to be a different kind of people — a "chosen generation" (1 Peter 2:9).