The word "戚戚" is formed by reduplicating the character "戚", which is a pictophonetic character composed of the radical "戈" (gé), historically associated with weapons or conflict, and the phonetic component "尗" (shū), which indicates its pronunciation; this repetition creates a disyllabic word that intensifies the original meaning of "戚" related to sorrow or worry, resulting in a term describing a state of deep anxiety or melancholy.