Definition of "subscript"

If the container is subscriptable and you remember the position where a particular piece of data was stored, you can use the subscript to efficiently retrieve the data.

2012, Robert Robson, Using the STL: The C++ Standard Template Library, page 249

As in the chapters on the synchronous model, we use the convention of subscripting a variable by the index of the process at which the variable resides.

1996, Nancy A. Lynch, Distributed Algorithms, Elsevier, page 210

The elements of these matrices are subscripted with a row–column index, that is, with two integers that give the row and column position in the array.

2011, William M. Davis (original author Cifford E. Dykstra), Physical Chemistry: A Modern Introduction (Second Edition), CRC Press, page 424

If your presentation covers chemistry or some other scientific field, you'll need to subscript and superscript characters (think H2O).

2007, Emily A. Vander Veer, PowerPoint 2007: The Missing Manual‎

Avoid subscripting arrays or hashes within loops.

2005, Damian Conway, Perl Best Practices