The Spanish word 'terror' comes directly from the Latin noun 'terror' meaning 'terror, fright'. This Latin noun was derived from the verb 'terreo' meaning 'to frighten' or 'to make tremble'. The word has maintained remarkably consistent form and meaning from Latin to modern Spanish.

Some related Spanish words include 'terrible' (terrible), 'terrorífico' (terrifying), and 'aterrorizar' (to terrorize). All these words share the same Latin root and convey similar meanings related to fear and dread.

English speakers will find this word very familiar as it's identical to the English word 'terror'. Both Spanish and English inherited this word from Latin. Other related English words include 'terrible', 'terrify', 'terrific' (which originally meant causing terror before evolving to mean excellent), and 'deter' (which literally means 'away from terror' or 'to frighten away').