the.com/root cause

means The original, underlying source of a problem — the deep cause that, if removed, would actually fix things, instead of just patching over the symptoms.

from A plain compound: 'root' borrowed from the plant world, where it means the hidden part that anchors and feeds everything visible above ground, and 'cause' from Latin 'causa,' meaning the reason behind an effect. The metaphor took hold because roots are literally what you must dig out to stop a weed returning — pull the leaf and it grows back, pull the root and it's gone. The phrase became common in problem-solving and engineering language (notably 'root cause analysis') in the 20th century, as industries formalized the practice of digging past symptoms to find what's actually feeding the trouble.