夆 ('to butt / meet head-on') is archaic and not used independently in modern Chinese. It survives as the phonetic in 峰 (mountain peak), 蜂 (bee), 锋 (sharp edge), 逢 (to meet / encounter), and 缝 (seam / to sew).
register
Archaic. The 'butt heads' reading is the one that explains its phonetic family; an older tradition also reads 夆 differently in rare classical use.