means To shout loudly, whether in anger, excitement, fear, or just to be heard across a distance.

from From Old English 'gellan' (also 'giellan'), meaning to shout or cry out — a word built from sound itself, part of a Germanic family that includes the noisy German 'gellen.' It's a close cousin of 'yelp' and is likely related to 'nightingale,' whose old name literally means 'night-singer.' The root is imitative: it sounds like the thing it describes.