Glossary

A semiglobal alignment of strings $s$ and $t$ is an alignment in which any gaps appearing as prefixes or suffixes of $s$ and $t$ do not contribute to the score of the alignment.

Semiglobal alignment arises because of the inherent weakness of global and local alignment to handle all practical applications. Other such hybrid methods (often formed into the portmanteau "glocal") include overlap alignment and fitting alignment.