In the last years many Islamic words have become familiar in the Western countries. Most of them are connected to the religion, history, social structures and traditions of the Islamic world, and are coming from the Holy Qur'$\bar{{\rm a}}$n and other Sacred Isl$\bar{{\rm a}}$m texts. They are a very important cultural and religious heritage for the Muslims. However, the meanings of how these words are used in the many documents and speeches made by radical authors are often fairly different from the traditional meaning. In some cases, most of all in the terrorists' speeches, the significance is totally changed. In this paper, we present the results of a comparative and evaluative analysis, started in 2009 and ended in February 2011, of a selected list of 37 Islamic words, such as Had$\bar{{\rm i}}$th, Im$\bar{{\rm a}}$m, Intif$\bar{{\rm a}}$dah, Jih$\bar{{\rm a}}$d. For every word, four aspects have been analyzed: 1) linguistic and semantic; 2) historical and evolutionary; 3) the word significance in radical thought; 4) stability (in time and space) of the semantic meaning.