百折不饶,字面意思

keep on fighting in spite of all setbacks,
be undaunted by repeated setbacks
be indomiteable

也可说成百折不回

百折不挠

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[拼音]：bǎi zhé bù náo
[解释]：
1.never to yield in spite of reverses;
to be undaunted by repeated setbacks;
to keep on fighting in spite of all setbacks;
not to lose heart despite repeated failures ;
keep on fighting in spite of all setbacks/be undaunted by repeated setbacks/be indomitable
[参考词典]：汉英综合科技大辞典 汉英综合大词典