the word 'tremor' entered english in the late 14th century from the old french 'tremour', which itself derived from the latin 'tremor', meaning 'a trembling'. this latin noun is an agent noun from the verb 'tremere', meaning 'to tremble'. the ultimate origin is the proto-indo-european root trem-, which carried the core meaning 'to tremble'. this root has given rise to a family of words across languages related to shaking or quivering, with 'tremor' in english specifically denoting a slight, often involuntary, shaking movement or vibration, whether physical or geological.

the word 'tremor' is a simplex loanword from latin. it is not productively formed from smaller, recognizable morphemes within modern english spelling and therefore is not segmented.