形容詞 downward:

1. on or toward a surface regarded as a base
2. extending or moving from a higher to a lower place
   同義詞：down

副詞 downward:

1. spatially or metaphorically from a higher to a lower level or position
   同義詞：down, downwards, downwardly

1. She laid the picture face downward on the table.
   她把那幅畫正面朝下放在桌上。
2. A downward incline or passage; a slope.
   斜面，斜坡向下的斜面; 傾斜面
3. The molten lava got into every nook and cranny on its downward path.
   熔巖向下流動時，無縫不鉆，無孔不入。
4. A downward movement; descent.
   向下的運動; 下降
5. The monkey was hanging head downwards from the branch.
   猴子頭向下倒掛在樹枝上。

down.ward

adv.（副詞）
adj.（形容詞）
From a higher to a lower place, point, level, or condition:
向下的，降下的：指位置、點、平面或條件由高處降到低處：
例句：
floating downward; a downward trend.
向下漂流；下降趨勢

From a prior source or earlier time:
往下：從一先前的來源或更早的時間來的：
例句：
passed downward through the ages.
一代代傳下來

【引伸】
down.wardly
adv.（副詞）
down.wards
adv.（副詞）