動(dòng)詞 define:

1. give a definition for the meaning of a word
2. determine the essential quality of
   同義詞：specify, delineate, delimit, delimitate
3. determine the nature of
4. show the form or outline of
   同義詞：delineate

1. Definitions should not be more difficult to understand than the words they define.
   詞語(yǔ)的定義不應(yīng)比所解釋的詞語(yǔ)更難理解。
2. When boundaries between countries are not clearly defined, there is usually trouble.
   國(guó)與國(guó)之間的邊界未明確劃定時(shí)，通常會(huì)發(fā)生糾紛。
3. The powers of a judge are defined by law.
   法官的權(quán)限是由法律規(guī)定的。

de.fine

v.（動(dòng)詞）
de.fined,de.fin.ing,de.fines
v.tr.（及物動(dòng)詞）

To state the precise meaning of (a word or sense of a word, for example).
給…下定義：給（例如，單詞或詞義）下精確的定義
To describe the nature or basic qualities of; explain:
闡釋：描述…的性質(zhì)或基本特征；解釋：
例句：
define the properties of a new drug; a study that defines people according to their median incomes.
解釋一種新藥的特性；根據(jù)人們的平均收入闡釋的調(diào)查

To delineate the outline or form of:
勾畫出…的輪廓或外形：
例句：
gentle hills that were defined against the sky.
在天空的襯托下顯得輪廓分明的丘陵

To specify distinctly:
清楚地規(guī)定：
例句：
define the weapons to be used in limited warfare.
明確地規(guī)定只能用于局部戰(zhàn)爭(zhēng)中的武器

To serve to distinguish; characterize:
用于分辨；顯示…的特色：
例句：
.portraits that defined the style of an epoch.(Gloria Vanderbilt)
.表現(xiàn)一個(gè)時(shí)代風(fēng)格特征的描寫.(格洛麗亞·范德比爾特)

v.intr.（不及物動(dòng)詞）
To make or write a definition.
下定義

來(lái)源：
Middle English definen, diffinen
中古英語(yǔ) definen, diffinen
from Old French definir, diffiner
源自 古法語(yǔ) definir, diffiner
from Latin dôfonore [to limit, determine]
源自 拉丁語(yǔ) dôfonore [限定，確定]
dô- [intensive pref.] * see de-
dô- [加強(qiáng)語(yǔ)意的前綴] *參見(jiàn) de-
fonis [boundary, limit]
fonis [邊界，界線]

【引伸】
defin.abil.ity
n.（名詞）
defin.able
adj.（形容詞）
defin.ably
adv.（副詞）
define.ment
n.（名詞）
defin.er
n.（名詞）