This is the 8th most frequent Indonesian word.
tidak
"Not" or "no."
Here, 'tidak' negates the adjective 'lapar' (hungry), indicating the absence of hunger.
Saya tidak lapar sekarang.
I am not hungry now.
In this sentence, 'tidak' negates the verb 'pergi' (go), indicating that the action of going did not occur.
Dia tidak pergi ke sekolah hari ini.
He/She did not go to school today.
Here, 'tidak' negates the adjective 'mahal' (expensive), specifying that the book does not have the quality of being expensive.