an overmatched person or group and a much stronger opponent in a contest or struggle
—The little boy is fighting a David and Goliath battle against the owners of the department store who say he can’t sell cookies in front of their building.

One of the Israelites’ enemies was the Philistines. Once, when the Israelite and Philistine armies were facing each other, a Philistine champion named Goliath came forward and challenged the Israelites to send a representative to fight him. Goliath was over 3 meters tall, and the Israelite soldiers were afraid of him. But a Jewish shepherd boy, David, trusted that God would help him defeat Goliath. With only a sling and five stones, he faced the giant, saying,

You are coming against me with sword and spear and javelin. But I am coming against you in the name of the Lord of hosts, the God of Israel’s armies, whom you have defied! This very day the Lord will deliver you into my hand! I will strike you down and cut off your head. (1 Samuel 17:45,46)

David slung a stone at the Philistine, striking him on the forehead. Goliath fell down, and David used the giant’s own sword to kill him. David became famous for his bravery and his devotion to God, later leading Israel as king. Goliath, on the other hand, is remembered mainly for his size. The name Goliath is now often used for someone or something that is very large or powerful, especially when compared to a smaller, weaker opponent.