This word (like the vast majority of words in Hebrew) comes from the bible, where it appears with niqqud: אִמָּא. Without the niqqud, you can't tell exactly how to pronounce it. That's why in modern Hebrew, which is written without Niqqud, we sometimes add י and ו to words.
The Academy of the Hebrew Language has set some rules that determine whether of not to add vowels to unclear words when writing without niqqud. According to those, it should be "אימא". However, these rules aren't strictly followed (virtually no one knows them), so there can be several common spellings of one word.
You guys are obviously all well versed in hebrew...this is the very beginning of my journey...it would be good to learn the alphabet and basics and have audio translations for every exercise...not just random....I have only just figured out that I must read from right to left....also the audio voices should be slowed down...the words come so fast and crash into each other that I cannot decifer anything!....do not suppose that we have some kind of working knowledge of the language...if we did we would not be here!!!...treat us as tiny infants who have to be taught from the very beginning...I am lost right now
To Simcha708017: Re Downloading Hebrew Keyboard: Step 1: Bottom right hand corner of monitor hit "ENG US" Language Preference add "+ add a language" Choose Hebrew עבר and press Step 2: Bottom right hand corner of monitor hit "Miniture keyboard symbol" List of your downloaded languages appear including the on-screen keyboard - Choose עבר Hebrew Start typing on the onscreen Hebrew keyboard Toggle between Hebrew and English