To contend with in battle; to war against; as, they fought the enemy in two pitched battles; the sloop fought the frigate for three hours.

A battle; an engagement; a contest in arms; a combat; a violent conflict or struggle for victory, between individuals or between armies, ships, or navies, etc.

A struggle or contest of any kind.

A screen for the combatants in ships.

the act of fighting; any contest or struggle; "a fight broke out at the hockey game"; "there was fighting in the streets"; "the unhappy couple got into a terrible scrap"

a hostile meeting of opposing military forces in the course of a war; "Grant won a decisive victory in the battle of Chickamauga"; "he lost his romantic ideas about war when he got into a real engagement"

be engaged in a fight; carry on a fight; "the tribesmen fought each other"; "Siblings are always fighting"

make a strenuous or labored effort; "She struggled for years to survive without welfare"; "He fought for breath"

exert oneself continuously, vigorously, or obtrusively to gain an end or engage in a crusade for a certain cause or person; be an advocate for; "The liberal party pushed for reforms"; "She is crusading for women's rights"; "The Dean is pushing for his favorite candidate"

Animal instinctual response when faced with danger to either face the threat (“fight”), or avoid the threat (“flight”).

(n) a hormonally stimulated state to prepare the body for an upcoming threat or challenge, brought on by the stimulation of the sympathetic nervous system, and consisting of such bodily changes as dilation of the bronchial tubes, increased heart rate and blood pressure, etc. It is sometimes evoked as a general reaction to stressful conditions, such as pressures on the job, and if continuous may lead to health problems such as hypertension and decreased immunity.

or-flight response - The body's first reaction to perceived stress.

mobilization of the bodies physiological defense mechanism as the body prepares for action.