The different activities that characterize the planning, sponsoring and execution of terrorist acts, measures and strategies for countering terrorism, lead to new terminological constructions in English and French. However, research shows that terminologists are yet to show interest in the study, analysis, and development of the field even though the daily activities, exchanges, debates, etc., involving specialists, scholars, researchers, politicians, stakeholders, or terrorists, who either perpetrate or fight against terrorism, lead to abundant lexical creativity. The present terminological inactivity in the field of terrorism may be, among other reasons, due to the fact that the definition of terrorism remains a purely theoretical issue and that one man’s terrorist often turns out to be another man’s freedom fighter. This study is an effort to remedy the terminological lacunae in the field of terrorism. It contributes to the increasing efforts to understand and document terrorism in all its ramifications. The study explores the concept of terrorism from the etymology of the term, its present lack of a generally acceptable definition, to the different reactions and measures for countering terrorism at both domestic (from the perspective of a select number of countries) and international (from the perspective of the international community—United Nations) levels. It explores the status of terrorism as a terminological domain with the aim of: a) analyzing the concepts and notional structures of the field of terrorism; b) identifying the terms assigned to the concepts; c) establishing correspondence between terrorism terms in French and their English equivalents; d) compiling a bilingual (French/English) lexicon for the subject field. The study highlights not only the functions of terminological units in different discourse contexts, but also the attitudes of humans in relation to term usage in a variety of cultural, ideological and religious contexts.