It's a nice question and quite hard to explain in English. :) But, let me try it. (Others are welcome to correct me if i'm wrong) "lupa" is a verb. and Indonesian language has "imbuhan", that contains : 1. awalan : you have to put "mem/ber/di" etc + word baca (verb) example : mem+baca = membaca 2. sisipan : you have to put "el/er" etc between the word gigi (noun) example : gigi+el = g(el)igi 3. akhiran : you have to put word + "an/kan" etc lupa (verb) example : lupa+kan = lupakan when you put "imbuhan" on word, you've change its meaning. lupa : verb - Ooo, saya lupa! / Ooo, i forgot! lupakan : verb + kan - Lupakan hal itu / Forget it! --> It became an imperative sentence. melupakan : me+ verb + kan - Saya melupakan kata sandi saya / I forgot my password. I hope that helps. *I really want to know the whole sentence from each word and where did you hear that. Words can have different meaning in different context, right? And I guess, when you learn Indonesian language, your question is on advanced level. Even for us, the native speakers. Good job and have a nice day. :)

Hi Jack, Maybe this link helps a bit: http://indodic.com/affixeng.html Selamat belajar! :)

lupakan is commad word, melupakan is verbs

Just add a sense Hi jack : meaning of 3 words is same. 3 Words Is verb, Dan, Difference between 3 words... in the Placement or the use of the phrase. Example : I'm forgot password my phone. Aku lupa kata kunci ponselku. Aku melupakan kata kunci ponselku. Aku lupakan kata kunci ponselku. 3 of words same meaning, but just one words correct. In Bahasa, there are rules :Baku dan Tidak baku. Example: In English : I'm reading book. In Bahasa : Saya sedang Baca buku <<< Tidak Baku. Saya sedang Membaca buku >>> Baku. Example : I'm forgot password my phone. Aku lupa kata kunci ponselku. Aku melupakan kata kunci ponselku. Aku lupakan kata kunci ponselku. 3 of words same meaning, but just one words correct. Well , kalimat, manakah yang benar?