inflexible

a. 不屈曲的, 不屈挠的, 顽固的

副词:inflexibly 名词:inflexibility 

in.flex.i.ble

adj.（形容词）
Not easily bent; stiff or rigid.
不易弯的，僵硬的：不易变曲的；强硬或生硬的
Incapable of being changed; unalterable.
不可能被改变的；不可变的
Unyielding in purpose, principle, or temper; immovable.
不屈挠的，不退让的：在目标、原则或个性上不屈挠的；坚定不可动摇的

【引伸】
inflex.ibil.ity 或
inflex.ibleness
n.（名词）
inflex.ibly
adv.（副词）
<参考词汇><同义词>inflexible,inexorable,adamant,obdurateThese adjectives mean not capable of being swayed or diverted from a course.
这些形容词表示不从既定路线上偏离或改变的。
Inflexible implies unyielding adherence to rigidly fixed principles or purposes:
inflexible 意指坚决遵照固定的原则或目标：
例句：
Polite but inflexible, she would not be deflected from her intention.
她礼貌但很坚决，绝不放弃自己的目标。

Inexorable implies lack of susceptibility to persuasion or entreaty:
Inexorable 意指难以说服，又不接受恳求：
例句：
.Cynthia was inexorable—she would have none of him. (Winston Churchill).The term also describes things, such as fate and law, that are inevitable, relentless, and often severe in effect:
辛西亚毫不动摇——她不要他的任何东西 （温斯顿·丘吉尔）。该词也用于描述事物（如具有不可抗力），通常有严峻效果的命运和法律：

例句：
.Russia`s final hour, it seemed, approached with inexorable certainty. (W. Bruce Lincoln).
俄罗斯的最后时刻，好象到了最严峻的时刻 (W·布鲁斯·林肯）。

Adamant usually implies imperviousness to pleas or appeals:
Adamant 通常暗示对请求或呼吁无动于衷：
例句：
He is adamant in his refusal to change his mind.
他毫不留情地拒绝改变主意。

Obdurate adds toadamant the implication of hard, unfeeling resistance to tender feelings:
Obdurate 一词在adamant 一词上又附加了一种不近人情的、冷酷无情的含义：
例句：
The child`s misery would move even the most obdurate heart. See also Synonyms at stiff
这个孩子所受的苦难会打动世界上最冷酷的心 参见同义词 stiff