Dictionary is considered as an identity for any nation, an instrument for development of language and a means for expressing the speakers' needs. And such needs are continuously modernized; and today, Arab world witnesses’ significant events; and along with these events, Arabic language is experiencing a change and is able to express such needs in any form. If modernism didn't happen in various scientific fields, the language would be abandoned and destroyed and we were obliged to deal with such development and influential factors so that no one could be able to accuse Arabic language of solidness and inflexibility. As dictionary is one of the most important means for second language teaching, this study attempts to conduct a comparison between novel terms in 'Almakenz Alkabir' (Ahmad Mokhtar, 2000 edition) and 'Almajam Alvasit' (published by Cairo Arabic Language Academy in 1960 – it enjoys an special status in cultural and scientific streams in Iran) dictionaries based on a descriptive-analytic method. The findings demonstrate that there are 1235 novel terms amounting to%3/57 in 'Almakenz Alkabir' dictionary and there are 459 novel terms amounting to%1/64 in 'Almajam Alvasit'; and the number of novel terms in Almakenz Alkabir is more than that in Almajam Alvasit because this dictionary considered any terms used after 4 th Hijrah century as a novel term.