The word 'telethon' is a modern portmanteau, a blend of two distinct elements. The first part, 'tele-', is derived from the Greek root meaning "at a distance," which became the standard prefix for television, a medium for transmitting images and sound over distance. The second part, '-thon', is a back-formation from 'marathon,' originally the site of a famous battle in Greece, later applied to the long-distance footrace, and finally abstracted into a suffix denoting any prolonged endurance event. Thus, a telethon logically combines the concept of a distant broadcast ('tele-') with that of an extended, marathon-like fundraising session ('-thon'), creating a term for a lengthy televised charity appeal.

Structure: tele (distant) + thon (event) - tele: From Greek tēle-, meaning "far off, distant." In English, it functions as a combining form relating to television or telecommunications. - thon: A suffix extracted from the word "marathon," itself from the Greek place name Marathōn. In modern English, it functions as a suffix meaning "a long-lasting event."