1Being certain or definite; having no doubt; clear and sure.
確かな証拠がない限り、その主張を受け入れられない。
Unless there is definite evidence, I cannot accept that claim.
それは確かな情報源からの報告だ。
That is a report from a reliable source.
彼女が成功するのは確かだと多くの人が言った。
Many people said it was certain that she would succeed.
2Reliable or trustworthy; sound and accurate in quality or performance.
このブランドの製品は値段は高いが、作りは確かだ。
This brand's products are expensive, but well made and reliable.
確かな技術を持った職人が修理してくれたので安心だ。
A craftsman with solid skills repaired it, so I'm reassured.
彼の話はいつも確かで、多くの人が信頼している。
His information is always reliable, and many people trust him.
3As an adverb meaning 'if I'm not mistaken' or 'as far as I recall,' used when the speaker is reasonably sure but not 100% certain.
確か、ミーティングは明日の午後３時からだと思います。
If I'm not mistaken, the meeting is at 3 PM tomorrow.
彼は確か以前この会社で働いていたはずだ。
I believe he used to work at this company.
確かに彼女はその本を持っていたが、今は見当たらない。
I do recall that she had that book, but it's not to be found now.