Definition (full): to feed on, to consume, to battle
Strong's Exhaustive Concordance
A primitive root; to feed on; figuratively, to consume; by implication, to battle (as destruction) -- devour, eat, X ever, fight(-ing), overcome, prevail, (make) war(-ring).
KJV: Come on, let us deal wisely with them; lest they multiply, and it come to pass, that, when there falleth out any war, they join also unto our enemies, and fight against us, and so get them up out of the land.
NASB: "Come, let us deal wisely with them, or else they will multiply and in the event of war, they will also join themselves to those who hate us, and fight against us and depart from the land."
KJV: And took off their chariot wheels, that they drave them heavily: so that the Egyptians said, Let us flee from the face of Israel; for the LORD fighteth for them against the Egyptians.
NASB: He caused their chariot wheels to swerve, and He made them drive with difficulty; so the Egyptians said, "Let us flee from Israel, for the LORD is fighting for them against the Egyptians."
KJV: And Moses said unto Joshua, Choose us out men, and go out, fight with Amalek: to morrow I will stand on the top of the hill with the rod of God in mine hand.
NASB: So Moses said to Joshua, "Choose men for us and go out, fight against Amalek. Tomorrow I will station myself on the top of the hill with the staff of God in my hand."