The word determined comes from Latin via Old French, tracing back to roots meaning "to mark out boundaries" or "to lmit".  It derives from the Latin verb determinare (to enclose or set limits), combining de- (off, out) and terminare (to bound or finish, from terminus, meaning end or limit) and the Old French déterminer ("to settle, decide, or define").  It was introduces into Middle English as determinen in the late 14th century meaning to settle, limit, or decide),  

According to the Oxford English Dictionary (OED), the earliest known use of the adjective determined dates back to 1546, appearing in the text Wycklyffes Wycket.  In the late 14th century the root verb determine and related forms like determinate were already active in Middle English via Geoffrey Chaucer and other writers, paving the way for the later adjective.  In the 1510s the verbal phrase to be determined (meaning to have resolved or made a decision) emerged.  It was finally "characterized by a firm resolution or fixity of purpose" by around 1600 for actions and 1772 for people.  

The concept of being "determined" serves as the vital engine of narrative momentum, transforming passive characters into active agents.  A character's firm resolution gives the plot a clear trajectory, converts abstract stakes into visceral conflict, and grounds emotional resonance so audiences care whether they succeed or fail.  

Core Functions of Determination:  
Drives the Plot: Moves the story forward from the inciting incident to the climax through purposeful action. Generates Conflict: Pits an unwavering goal against escalating obstacles, forcing meaningful choices.  
Builds Empathy: Proves character values through sacrifice, making struggle meaningful rather than arbitrary.  
Proves Theme: Demonstrates the ultimate cost or truth of the narrative through persistent effort.  

Impact on Audience Engagement:  
Raises the Stakes: Makes every setback feel heavy because the character refuses to quit.  
Creates Catharsis: Delivers a satisfying payoff when resolution matches earned effort.  
Prevents Stagnation: Stops narratives from stalling when external circumstances overwhelm the protagonist.  

Just the facts:

DETERMINED Definition & Meaning - Merriam-Webster

DETERMINED Synonyms: 279 Similar and Opposite Words | Merriam-Webster Thesaurus

DETERMINE Definition & Meaning - Merriam-Webster

DETERMINATION Definition & Meaning - Merriam-Webster

SELF-DETERMINED Definition & Meaning - Merriam-Webster

BOUND AND DETERMINED Definition & Meaning - Merriam-Webster

During my search today I came across the word 'cowardly', I only mention this because I saw that one of its adjectives was pusillanimous. Ever since I first saw, The Wizard of Oz, over sixty years I had wondered what it meant and now I know!

In The Wizard of Oz, the word pusillanimous (meaning cowardly or lacking courage) is famously used by the Wizard when talking to the Scarecrow: "Every pusillanimous creature that crawls on the Earth or slinks through slimy seas has a brain." 

The Wizard Of OZ 1939 720p (time1:29-1:33) - YouTube

The following, if you have sometime, is an eye opener!

THE WIZARD OF OZ (1939): Cast Then & Now — The Secrets Hidden Behind The Most Beloved Film Ever Made - YouTube

Rest in Peace, Judy Garland, somewhere over the rainbow.