  This paper introduces the sequence covering similarity, that we formally
define for evaluating the similarity between a symbolic sequence (string) and a
set of symbolic sequences (strings). From this covering similarity we derive a
pair-wise distance to compare two symbolic sequences. We show that this
covering distance is a semimetric. Few examples are given to show how this
string metric in $O(n \cdot log n)$ compares with the Levenshtein's distance
that is in $O(n^2)$. A final example presents its application to plagiarism
detection.
