Final answer:
Kennedy's 'New Frontier' terminology was meant to inspire Americans to engage in progressive change, reflecting optimism and the desire to tackle various domestic and international challenges during his administration.
Step-by-step explanation:
President John F. Kennedy used words like 'pathfinders' and 'pioneers' and referred to his vision as the 'New Frontier' to evoke a sense of optimism and challenge Americans to embrace change and progress. The New Frontier concept was a metaphor for tackling new challenges, both domestically with initiatives aimed at ending racial injustice, poverty, and improving civil rights, and internationally with goals such as winning the space race against the Soviet Union. Liberals and other citizens saw the New Frontier as an opportunity to renew the nation's pioneer spirit, with ambitious programs such as the Peace Corps and advancements in space technology representing American ingenuity and dedication to progress.