A variable length string is usually ended with a null (\0) character. Most often referenced by a char pointer, since they will royally screw up a typical data structure (as everything after the string will be at an indeterminate position), they are what all those str functions manipulate.


The old writeup (preserved for posterior(sic)):
A string of variable length. This should be obvious.

A variable length string is also a self-explaining term.