"not applicable" is correct and usable in written English. You can use it when something is irrelevant, or does not apply to a particular scenario or situation. Example sentence: "The rules for this tournament do not apply to participants under the age of 18; therefore, the age restriction is not applicable.".
Not applicable.
That stands for not applicable.
Favorite place to shop: Not applicable.
not applicable.
It is not applicable.
NA: not applicable.
N.A. = Not Applicable.
Awesome tool! I started using it one year ago and I never had to look for another app
Ha Thuy Vy
MA of Applied Linguistic, Maquarie University, Australia