vestige

noun

1. A mark left on the earth by a foot.
2. (broadly)A faint mark or visible sign left by something which is lost, or has perished, or is no longer present.

   “the vestiges of ancient magnificence in Palmyra”

   “vestiges of former population”

   “The result, therefore, of this physical inquiry is, that we find no vestige of a beginning,— no prospect of an end.”

   “Her face was without a vestige of colour, but it only showed more strongly the perfect outline of her features. Pale she was, but not like a statue; it was a human paleness—passionate and painful.”

   “Nevertheless in some cases, my original view, that the points are vestiges of the tips of formerly erect and pointed ears, still seems to me probable.”

3. A vestigial organ; a non-functional organ or body part that was once functional in an evolutionary ancestor.

   “Any person seeing such a condition could not help being frightened at the conditions found, and it seems to me that that fact should lead us to think that the appendix is a vestige or becoming so.”

   “Now this paired organ of Jacobsen began in reptiles and is well developed in many mammals. But in man it is a vestige, often disappearing altogether; and the two openings are closed.”

   “This idea was confirmed by Scott, who performed a detailed comparative analysis of primate anatomy and demonstrated conclusively that the appendix is derived for some unidentified function and is not a vestige.”

4. The remaining portion of a partially suppressed sideband.

   “[J]ust a trace, or vestige, of the other sideband is included. In the receiver detection circuitry the vestige of the lower sideband is added to the upper sideband.”