The compound adjective 'terrorism-related' is a modern formation built from two established English words. The first element, 'terrorism', originates from the Latin verb terrere, meaning 'to frighten or terrify', combined with the noun-forming suffix -ism to denote a specific doctrine or practice—in this case, the systematic use of terror for political aims. The second element, 'related', stems from the Latin referre ('to carry back, report'), whose past participle relatus evolved to mean 'connected or associated'. When combined, these morphemes create a precise, attributive term used primarily in legal, journalistic, and political discourse to categorize any person, activity, or material that has a connection to the practice of terrorism, reflecting the lexical need for efficient classification in contemporary security contexts.

Structure: terrorism (act of terror) + related (connected) terrorism: From Latin terrere (to frighten) + English suffix -ism (denoting a practice or system). In this compound, it functions as the core noun. related: From Latin relatus (brought back, referred), past participle of referre. In this compound, it functions as a participial adjective meaning 'connected'.