moxie

1. The ability to face difficulty with spirit and courage.
2. Aggressive energy; initiative: "His prose has moxie, though it rushes and stumbles from a pent-up surge" (Patricia Hampl).
3. Skill; know-how.

[From Moxie, trademark for a soft drink.]

(MOK-see)

noun
1. The ability to face difficulty with spirit and courage.
2. Aggressive energy; initiative.
3. Skill; know-how.

Etymology
From Moxie, trademark for a soft drink.

noun

The quality of mind enabling one to face danger or hardship resolutely: braveness, bravery, courage, courageousness, dauntlessness, doughtiness, fearlessness, fortitude, gallantry, gameness, heart, intrepidity, intrepidness, mettle, nerve, pluck, pluckiness, spirit, stoutheartedness, undauntedness, valiance, valiancy, valiantness, valor. Informal spunk, spunkiness. Slang gut (used in plural), gutsiness. See fear/courage.

The twentieth century may pride itself on miracles of modern medicine, but it's not the first; the nineteenth century was not shy about medical miracles of its own. It was the great era of the Cure-all (1821). Moxie had its beginning as the name for a medical marvel of this kind, invented in 1876 by Dr. Augustin Thompson of Union, Maine. If we are to believe the label on its 26-ounce bottles, this Moxie worked better than any twentieth-century wonder drug (1939): it claimed to cure "brain and nervous exhaustion, loss of manhood, imbecility and helplessness.... It gives a durable solid strength, and makes you eat voraciously; takes away the tired, sleepy, lifeless feeling like magic, removes fatigue from mental and physical overwork at once."

According to the label, Moxie was named after a Lieutenant Moxie, who discovered the active ingredient, "a simple sugarcane-like plant grown near the Equator and farther south." But Frederic Cassidy, editor of the Dictionary of American Regional English, suspects that both the lieutenant and the plant may be inventions. Dr. Thompson could have gotten the name of his tonic much closer at hand, from a plant called a moxie-berry that was used in Maine by Indians, and then by settlers, to make medicinal tea.

In the twentieth century, federal drug laws removed the extravagant claims from the Moxie label. But a Boston softdrink manufacturer took over the Moxie name in the 1920s, applied it to a fizzy drink made with gentian root, and perpetuated its vigorous connotations so successfully that by the 1930s moxie had acquired a new life independent of the beverage. It had become a slang synonym for strength, energy, courage, and mental sharpness combined.

The noun has one meaning:

Meaning #1: (informal) fortitude and determination
  Synonyms: backbone, grit, guts, sand, gumption