vestigial
"Vestigial" describes a part of an organism or a trait that has become functionless or significantly reduced in size through the process of evolution. Imagine a structure that was once vital to an ancestor but is now just a lingering, shrunken echo of its former self—like a tailbone in humans or the tiny, useless pelvic bones found in some whales. In a broader, metaphorical sense, the word is used to describe something that persists in a diminished state, long after its original purpose or context has vanished. You might describe a "vestigial sense of guilt" or a "vestigial custom" that people continue to follow even though they have forgotten why it started. It carries a tone of historical leftover or an evolutionary relic.
Examples
The whale's hip bones are a vestigial remnant of its land-dwelling ancestors.
The whale's hip bones are a vestigial remnant of its land-dwelling ancestors.
Despite the company's modernization, a vestigial bureaucracy still slows down every decision.
Despite the company's modernization, a vestigial bureaucracy still slows down every decision.
He felt a vestigial flicker of resentment toward his rival, though the competition had ended years ago.
He felt a vestigial flicker of resentment toward his rival, though the competition had ended years ago.
