汉语翻译：
num. 第四, 四分之一英语解释：
名词 fourth:

following the third position; number four in a countable series

one of four equal parts同义词：one-fourth, quarter, fourth part, twenty-five percent, quartern

the musical interval between one note and another four notes away from it

形容词 fourth:

coming next after the third and just before the fifth in position or time or degree or magnitude同义词：4th, quaternary

副词 fourth:

in the fourth place同义词：fourthly

例句：

I can't do the fourth and fifth questions but I've done all the others.第四题和第五题我不会，但是剩下的我都答了。

After her fourth child she decided to be/have herself sterilized.她生了第四个孩子後决定做绝育手术。

Mars is the fourth planet in order from the sun.火星是太阳系的第四颗行星。

Time is sometimes called the fourth dimension.时间有时被称为第四度空间。

One fourth of a yard; nine inches.四分之一码; 九英寸

I am a soldier of the fourth cavalry.我是第四骑兵部队的一员。

One fourth of a ton;500 pounds. Used as a measure of grain.五百磅四分之一吨; 五百磅。用作谷物计量单位

After her fourth child she decided to have herself sterilized.她生了第四个孩子后决定做绝育手术。

详细解释：
fourth
n.（名词）
The ordinal number matching the number four in a series.
第四：一序数词，一列数中的第四个
One of four equal parts.
四分之一
Music
【音乐】
A tone four degrees above or below a given tone in a diatonic scale.
第四音级：自然音阶中高于或低于一给出音调四度的音调
The interval between two such tones.
四度音程：两音调之间的间歇
The harmonic combination of these tones.
四度和音：音调的和谐组合
The subdominant in a scale.
下属音
The transmission gear or gear ratio used to produce forward speeds next higher to those of third in a motor vehicle.
第四档：海车换挡时从第三挡换到下一挡，以加快速度
Fourth The Fourth of July; Independence Day.
Fourth 美独立纪念日：7月4日；美国独立纪念日
来源：
Middle English fourthe
中古英语 fourthe
from Old English fôorth3 * see k wetwer-
源自 古英语 fôorth3 *参见 k wetwer-
【引伸】
fourth
adv.（副词）
adj.（形容词）

one fourth