IPA: /ˈlɛvəlˌhɛdədnəs/
KK: /ˈlɛvəlˌhɛdɪdnəs/
The quality of being calm and sensible, especially in difficult situations.
Her levelheadedness during the crisis helped everyone stay focused and calm.
Levelheadedness → It is formed from "level" (from Old French *livelle*, meaning even or flat) and "headed" (from "head", meaning the top or leader) combined with the suffix "-ness" (meaning the state of being). The word describes the state of being calm and sensible, as if one's head is level and balanced.
Think of being 'even' or 'flat' ('level') in your thoughts, which helps you stay calm and sensible — that's what levelheadedness means.