window box
noun [ C ] uk/ˈwɪn.dəʊ ˌbɒks/ us/ˈwɪn.doʊ ˌbɑːks/
（窗沿上装土用来种植植物的）窗口花坛
a box filled with earth, for growing decorative plants in, positioned on an outside windowsill
window boxes full of brightly coloured geraniums 长满鲜艳夺目的天竺葵的窗口花坛