The verb 'tell' originates from the Old English 'tellan', which carried the core meaning of counting, recounting, or relating a narrative. This sense of enumeration or narration evolved to encompass the broader act of communicating information. The addition of the participial suffix '-ing' transforms the action into a descriptive quality, leading to the modern adjective 'telling'. It describes something that effectively 'recounts' or 'reveals' a significant truth, thereby linking the ancient concept of giving an account to the contemporary idea of being revealing or significant.

Structure: tell (to relate, to count) + ing (adjective-forming suffix) 'tell' is from Old English 'tellan', meaning "to reckon, account, consider," of Germanic origin. 'ing' is a suffix forming present participles and adjectives from verbs, of Old English origin.