crux
UK: krʌks | US: krʌks
n. the most important or difficult part of a problem or issue
n. (literary) a cross, especially as a symbol in heraldry or religion
The word "crux" comes directly from Latin crux, meaning "cross." In Latin, it referred both to the physical object (a cross) and metaphorically to a "torture" or "trouble," as crosses were used for executions. Over time, English adopted it to signify the pivotal or most challenging point of an issue, drawing from the idea of a cross as a central or burdensome symbol. The heraldic/religious sense retains the original Latin meaning.
The crux of the debate lies in balancing economic growth and environmental protection.
Understanding this theorem is the crux of passing the advanced math course.
Medieval manuscripts often depict the crux as a symbol of faith.
His argument missed the crux of the problem entirely.
The team finally addressed the crux of the software bug after weeks of testing.