When a group or a person cares about one thing over all others, that’s the top priority. “After the flood, finding a place to live became their first priority.”
Priority comes from the word prior, which means to come before something else. A priority is the concern, interest or desire that comes before all others. “His first priority was to establish his career and get married later.” “When seeking the perfect wave, Jeff and Wayne made it their priority to be the first surfers on the beach.” "The new CEO's top priority was firing her predecessor's hires."