The word 'yelling' is built upon the Old English verb 'giellan', meaning to shout or make a harsh sound, which itself has Proto-Germanic origins. The addition of the '-ing' suffix, a productive morpheme in English since its earliest stages, transforms the action into a noun denoting the act or continuous state of shouting, or into an adjective describing someone who is engaged in that action. The core semantic thread from its ancient root to modern usage consistently conveys the production of a loud, often strident, vocal cry. This straightforward morphological structure clearly illustrates how a basic action verb is grammatically adapted to serve different syntactic roles within the language.

Structure: yell (to shout) + ing (present participle suffix) - yell: From Old English giellan, gellan (to yell, to sound harshly), of Germanic origin. It functions as the core verb root. - ing: A suffix from Old English -ende, -unge, used to form the present participle or a verbal noun.