Definition: determined; resolute; indefatigable, implacable

• Dare, dream, dance, smile, and sing loudly! And have faith that love is an unstoppable force! — Suzanne Brockmann (1960-) American writer
• God steps into the suffering with us, and He takes it on himself, and He walks through it with us, and He uses it to create something in you that is unstoppable. — Kirk Cameron (1970-) American actor