確か

たしか

if I remember correctly; certain, definite

na-adjective

Conjugation Table

Present

確かだ

Negative

確かじゃない

Past

確かだった

Past Negative

確かじゃなかった

Te Form

確かで

Adverbial

確かに

Conditional

確かなら

Presumptive

確かでしょう

Example Sentences

彼は確かに医者です。

He is definitely a doctor.

Kare wa tashika ni isha desu.

昨日見た映画は確かによかった。

The movie we watched yesterday was certainly good.

Kinou mita eiga wa tashika ni yokatta.

彼女の名前は確かじゃない。

I’m not sure about her name.

Kanojo no namae wa tashika ja nai.

Grammar Notes & Usage Tips

•Na-Adjective Basics**: 確か (たしか) is a na-adjective, so when you want to use it to describe a noun, remember to add な, like in 確かな情報 (たしかなじょうほう) for "certain information."

•Expressing Uncertainty**: When you use 確か at the beginning of a sentence, it often means "if I remember correctly" or "I think," like in 確か、彼は来ると思います (たしか、かれはくるとおもいます), which translates to "I think he is coming."

•Particle Usage with Nouns**: When using 確か to modify a noun directly, don't forget the な particle, but if you're using it as a predicate, drop the な, as in この情報は確かです (このじょうほうはたしかです) meaning "This information is certain."

•Negative Form**: To express uncertainty or doubt, use the negative form 確かではない (たしかではない) or 確かじゃない (たしかじゃない), such as in その話は確かじゃない (そのはなしはたしかじゃない), meaning "That story isn't certain."

•な-adjective: Uses な before nouns, conjugates like a noun