直す|なおす

1. 1Redo an action from the start because the first attempt contained a mistake.Ex. 1
2. 2Do something again in order to revise or improve the result.Ex. 2
3. 3Simply do an action once more, such as rereading or re-listening, without implying the first attempt was flawed.

Neutral in register and common in both speech and writing. It is typical of work, study and everyday tasks: recalculating, rewriting, re-reading or re-listening. Compared with もう一度 plus a verb, ～直す often suggests correcting or improving the earlier result, but with verbs such as 読む or 聞く it can also mean simply doing the action again.

• 続けるN4「続ける」also attaches to the ます-form, but means an action continues without interruption or is kept up, with no implication that it was done wrong before; 「直す」means redoing something to correct or improve it. The two differ in meaning and cannot be interchanged.
• きるN3「きる」also attaches to the ます-form, but means completing an action thoroughly or bringing a state to its extreme, with no sense of redoing. 「書ききる」means writing everything to the end, while「書き直す」means rewriting, so the two cannot be interchanged.
• 出すN4「出す」also attaches to the ます-form, but means an action, emotion, or phenomenon like rain begins to occur, often with a sudden nuance; 「直す」means redoing or reconsidering something to correct or improve it. The two differ in meaning and cannot be interchanged.
• 始めるN4「始める」also attaches to the ます-form, but only marks the start of an action or natural change (as in「書き始める」), with no implication that what was done before was wrong or not good enough; 「直す」means redoing or re-examining something to correct or improve it. The two cannot be interchanged.
• 終わるN4「終わる」means finishing a continuing action ('finish doing...'), with no premise of error or dissatisfaction; 「直す」means redoing or re-examining because something was wrong or unsatisfactory. Both attach to the ます-form, but they differ in meaning and cannot be interchanged.
• かけるN3「かける」also attaches to the ます-form, but means an action is left half-done or something almost happens; 「直す」means redoing or re-examining because something was wrong or unsatisfactory. For example,「書きかけ」means half-written, while「書き直し」means rewriting, so the two cannot be interchanged.

「続ける」「始める」「出す」「かける」「終わる」「きる」all attach to the ます-form, but they mainly indicate how far an action progresses: 「始める」and「出す」mean starting, 「続ける」means continuing, 「かける」means doing halfway, and 「終わる」and「きる」mean finishing or completing thoroughly — none implies that what was done before was wrong or not good enough. 「直す」, by contrast, means redoing or re-examining something because it was wrong or unsatisfactory, focusing on correcting or improving the result, as in「書き直す」(rewrite), and cannot be swapped with any of the above.