to shoot with a gun (often fol. by down): The guards gunned down the fleeing convict.
9.
to cause (an engine, vehicle, aircraft, etc.) to increase in speed very quickly by increasing the supply of fuel.
–verb (used without object)
10.
to hunt with a gun.
11.
to shoot with a gun.
—Verb phrase
12.
gun for,
a.
to seek with intent to harm or kill.
b.
to seek; try earnestly to obtain: He is gunning for a raise.
—Idioms
13.
give the gun, Slang. to put into motion or speed up: We gave the motor the gun and drove off.
14.
jump the gun, Slang.
a.
to begin a race before the starting signal.
b.
to begin prematurely; act too hastily.
15.
spike someone's guns, to frustrate or prevent someone from accomplishing a plan: Our competitors planned a surprise reduction in their rates, but we discovered it and were able to spike their guns.
16.
stick to one's guns, to maintain one's position in the face of opposition; stand firm: They stuck to their guns and refused to submit. Also, stand by one's guns.
17.
under the gun, under pressure, as to meet a deadline or solve a problem: We're all under the gun with these new sales quotas.
Origin: 1300–50; ME gunne, gonne, appar. short for AL Gunilda, gonnyld, name for engine of war; cf. ON Gunna, short for Gunnhildr woman's name
A weapon consisting of a metal tube from which a projectile is fired at high velocity into a relatively flat trajectory.
A cannon with a long barrel and a relatively low angle of fire.
A portable firearm, such as a rifle or revolver.
A device resembling a firearm or cannon, as in its ability to project something, such as grease, under pressure or at great speed.
A discharge of a firearm or cannon as a signal or salute.
One, such as a hunter, who carries or uses a gun.
A person skilled in the use of a gun.
A professional killer: a hired gun.
The throttle of an engine, as of an automobile.
v.
gunned, gun·ning, guns
v.
tr.
To shoot (a person): a bank robber who was gunned down by the police.
To open the throttle of (an engine) so as to accelerate: gunned the engine and sped off.
Maine To hunt (game).
v.
intr. To hunt with a gun. Phrasal Verb(s): gun for
To pursue relentlessly so as to overcome or destroy.
To go after in earnest; set out to obtain: gunning for a promotion.
Idiom(s):
go great gunsTo proceed or perform with great speed, skill, or success.
Idiom(s):
hold a gun to (someone's) headTo put pressure on someone.
Idiom(s):
under the gunUnder great pressure or under threat.
[Middle English gonne, cannon, short for Gunilda, woman's name applied to a siege engine, from Old Norse Gunnhildr, woman's name : gunnr, war; see gwhen- in Indo-European roots + hildr, war.]
Pursue relentlessly so as to overcome or destroy. For example, He was sure they were gunning for him and asked for police protection, or The senator felt that the reporters were gunning for him with that article about his brother. [Slang; late 1800s]
Go after in earnest, try hard to obtain. For example, He's been gunning for a raise all year. [Slang; mid-1900s]
[guhn] 
noun, verb, gunned, gun⋅ning.