Loud has 8 different meanings across 3 categories:
A loud sound or part of a sound.
"The loud crack of thunder echoed across the valley."
In plain English: A loud is an informal term for someone who makes excessive noise, often annoying others around them.
"The loud from the construction site kept me awake all night."
characterized by or producing sound of great volume or intensity
"a group of loud children"
"loud thunder"
"her voice was too loud"
"loud trombones"
Of great intensity.
"The thunder crashed down with such loud force that the windows rattled in their frames."
A surname.
"Several Louds gathered at the county fair to support their local team."
The word "loud" comes from Old English hlūd, which originally meant loud, noisy, or sounding. It traveled into Middle and then Modern English with this same meaning of making a lot of noise.