The term "dragon" in the Bible refers to many large and frightening land or sea creatures. But, it does not mean the fire-breathing, winged reptiles of European myths.
The translators of the King James Version chose this term to translate two Hebrew words. These words are often translated more accurately in modern versions. One word refers to desert animals. Most scholars agree it means "jackals," as in the New International Version (Psalm 44:19; Isaiah 13:22; Jeremiah 9:11; Malachi 1:3). See Jackal.
The other Hebrew word translated as “dragon” is harder to define. It was often used to refer to serpents (Exodus 7:9–12; Deuteronomy 32:33; Psalm 91:13). It is also translated as “sea monster” in the Revised Standard Version (Genesis 1:21; Job 7:12; Psalm 148:7). We do not know what the sea monsters were.
Some passages in the Revised Standard Version are translated as “dragon.” In two of them (Psalm 74:13; Isaiah 27:1), the context indicates a sea monster. In three others “dragon” seems to refer to a crocodile (Isaiah 51:9; Ezekiel 29:3; 32:2) . This would be a symbolic reference to the Egyptian pharaoh at the time of the exodus. In Jeremiah 51:34 “monster” may also refer to a devouring creature like the crocodile. See Crocodile.
Babylonian myths depicted monsters and dragons battling the god Marduk, symbolizing evil. Similarly, the term "dragon" in Scripture, especially in prophetic books, carries this meaning. In Revelation, it specifically represents Satan, God's greatest enemy (Revelation 12:3–17; 13:2, 4, 11; 16:13; 20:2).