constant

continual, continuous, successive, constant, persistent

这些形容词均有“连续的”、“不断的”之意。
continual: 强调重复或持续发生，但连续之间允许有间断。
continuous: 语意最强，强调在时间和空间上没有间断。
successive: 强调事物一个接一个地发生，无间断。
constant: 多指习惯性的重复和不变的持续。
persistent: 普通用词，可指不懈的努力，也可指任何连续不断或重复出现的事物。

名词 constant:

1. a quantity that does not vary
   同义词：constant quantity, invariable
2. a number representing a quantity assumed to have a fixed value in a specified mathematical context

形容词 constant:

1. persistent in occurrence and unvarying in nature
   同义词：changeless, invariant, unvarying
2. continually recurring or continuing without interruption
   同义词：continuant
3. steadfast in purpose or devotion or affection
4. uninterrupted in time and indefinitely long continuing
   同义词：ceaseless, incessant, never-ending, perpetual, unceasing, unremitting

1. This has been a timely reminder of the need for constant care.
   这件事适时地提醒我们要注意时时谨慎。
2. The children's constant chatter was irritating.
   那些孩子们喋喋不休的说话声使人心烦。
3. The fear of being discovered was his constant companion.
   他总提心吊胆的，担心被人发现。
4. She feels wearisome by the constant noise.
   她很厌烦那些没完没了的嘈杂声。
5. In computer graphics, to enlarge or reduce all or part of a display image by multiplying their coordinate by constant values.
   在计算机图形学中，以常数值乘以图象的坐标来放大或缩小全部或部分显示图象。
6. A constant, or field, usually at the top of a page or display, that identifies the information on the page or display.
   通常出现在页面或显示屏顶部的一种常数或字段，用于标识页面或显示屏的信息。
7. The machinery requires constant maintenance.
   这些机器需要经常保养维修。
8. He drove at a constant speed.
   他以稳定的速度开车。

con.stant

adj.（形容词）
Continually occurring; persistent.
持续的：连续发生的；持续不断的
Unchanging in nature, value, or extent; invariable.See Synonyms at continual
永恒的：在性质、价值或范围上持久不变的；始终如一的参见 continual
Steadfast in purpose, loyalty, or affection; faithful.See Synonyms at faithful ,steady
坚定：在目的、忠诚或感情上坚定不移的；忠诚的参见 faithful,steady
n.（名词）
Something that is unchanging or invariable.
不变的事物：持久不变或始终如一的事物
Abbr. c,C,const.
缩写 c,C,const.
A quantity assumed to have a fixed value in a specified mathematical context.
恒量：在一个具体数学问题里被假设具有固定值的一个量
An experimental or theoretical condition, factor, or quantity that does not vary or that is regarded as invariant in specified circumstances.
永恒值：不变的或在具体环境中被认为不变的一个实验上或理论上的条件、因素或数量

来源：
Middle English
中古英语
from Old French
源自 古法语
from Latin cônst3ns cônstant- [present participle of] cônst3re [to stand firm]
源自 拉丁语 cônst3ns cônstant- [] cônst3re的现在分词 [站稳]
com- [intensive pref.] * see com-
com- [前缀，表加强词意] *参见 com-
st3re [to stand] * see st3-
st3re [站立] *参见 st3-

【引伸】
con.stantly
adv.（副词）