The compound noun 'truth-teller' is a transparent formation from native English elements. Its first component, 'truth', originates from the Old English abstract noun 'trēowth', which itself is built on the Germanic root for 'firm' or 'steadfast', evolving to signify conformity to fact or reality. The second element, the agent noun derived from the verb 'tell', has ancient roots in the Proto-Germanic verb meaning 'to count' or 'to relate', a sense preserved in terms like 'bank teller'. Combined with the agent suffix '-er', the word's literal construction as 'one who narrates truth' directly and logically conveys its modern meaning of a person habitually honest or one who exposes hidden realities.

Structure: truth (true) + tell (to narrate) + er (agent suffix) truth: From Old English 'trēowth', meaning 'faithfulness, constancy'. A noun-forming suffix derived from the adjective 'true'. tell: From Old English 'tellan', meaning 'to reckon, account, narrate'. A verb root meaning to give an account or information. er: From Old English '-ere', an agent noun suffix indicating a person who performs an action.