The stemming is the process of transforming a word into its root or stem,hence, it is considered as a crucial pre-processing step before tackling any task of natural language processing or information retrieval. However, in the case of Arabic language, finding an effective stemming algorithm seems to be quite difficult, since the Arabic language has a specific morphology, which is different from many other languages. Although, there exist several algorithms in literature addressing the Arabic stemming issue, unfortunately, most of them are restricted to a limited number of words, present some confusions between original letters and affixes, and usually employ dictionary of words or patterns. For that purpose, we propose the design and implementation of a novel Arabic light stemmer, which is based on some new rules for stripping prefixes, suffixes and infixes in a smart way. And in our knowledge, it is the first work dealing with Arabic infixes with regards to their irregular rules. The empirical evaluation was conducted on a new Arabic data-set (called ARASTEM), which was conceived and collected from several Arabic discussion forums containing dialectical Arabic and modern pseudo-Arabic languages. Hence, we present a comparative investigation between our new stemmer and other existing stemmers using Paice’s parameters, namely: Under Stemming Index (UI), Over Stemming Index (OI) and Stemming Weight (SW). Results show that the proposed Arabic light stemmer maintains consistently high performances and outperforms several existing light stemmers.