The Chinese idiom "红杏出墙" is formed by directly combining the nominal element "红杏" (red apricot, denoting apricot branches with blossoms) with the verbal element "出墙" (to exit the wall), constructing a literal depiction of apricot branches extending beyond a wall, which originated from a descriptive poetic image and subsequently solidified into a fixed four-character expression with an acquired metaphorical sense.