"My age is a secret"


My online language class taught us how to reply with our age(s) in a sentence.
We were also told that you could reply with "naisho" meaning secret if you
weren't going to provide your age. However, I've not seen anywhere that uses
this term in a sentence. How do say this correctly in Japanese and not just
use a one word response of naisho? Such as "my age is a secret."




内緒【ないしょ】 (naisho) functions as a simple noun (although it also works as a so-
called "no-adjective"). You already know how to say "This is a pen" or "I am a
student" in Japanese, right? Then you can employ the exact same grammar.

> 私【わたし】の年【とし】は内緒【ないしょ】です。  
>  My age is a secret.

This is the "full" sentence, but people usually do not bother to repeat the
topic (私の年) when it has been already clearly indicated in the previous
question:

> 内緒です。  
>  (It's) a secret.

And in casual speech, です is often omitted. So actually a one-word response is
not bad in this case:

> 内緒。  
>  (It's) a secret.

