TREMBLE points to TAX, TAXA, TAXI and in medical parlance to ATAXIA. These terms focus on "disordered" movements as in DASH, a characteristic of hunting hounds called DACHS-hounds or dachshunds, also known as TAXA.
From Greek and Latin TRERON and TERO emerged TEAR, FEAR, TERROR, bruise, afraid, TERRIBILIS and TERRITORIUM for TERRIBLE TERRITORY.
GAIA or TERRA combined with VULCAN as per volcanic TERRAins or TERRItories points to TREMBLE where TERRIFYING TERRIBLE TERREMOTOS take place.
TERRORISM implies a combination of TERROR with ZEAL. When in 1870, "The Peoples Freedom" revolutionary group announced that it was a Russian TERRORIST organization, the term gained global attention. In 1880, inspired by real events, Dostoyevsky wrote the "The Possessed" and exposed the deformed souls of TERRORISTS. Once in power, the Bolsheviks forbade "The Possessed", since it was inimical to their reliance on state terrorism. Modern TERRORISM, ignited by IDEALS or RELIGION and sustained by FANATIC ZEAL that defies doubt and reason, combines TERROR with SUBVERSION, VIOLENCE directed at innocent VICTIMS. ZEAL, ZEALOTRY, and JEALOUSY open vistas to extremes of love, sexual drive, fervor and fanaticism. The ancients coined ZELUS, ZELOS or CELOS in Latin, Greek and Spanish to denote "sexual heat", a drive to "pair or mate", "bonding" "sexual craving" and "being in heat". Such ancient roots are consonant with many young terrorists who "sublimate" or redirect their sexuality toward more exalted religious (celibacy) or political ideals (partisan revolutionaries). A grand example of excessive ZEAL and JEALOUSY is given by Shakespeares Otello whose cruel pitiless love for Desdemona destroyed both.
... for the assassin it is
an act of war ...
a transplant of ideals into crime ..."
(Jose Antonio Marina)