subscript

Short definition from Wiktionary

Noun

1. 1
   A type of lettering form written lower than the things around it.
2. 2
   An index into an array or hash.

Verb

1. 1
   To provide with a subscript.
2. 2
   To convert to a subscript form.
3. 3
   To access (an array element) by its index.

Adjective

1. 1
   Written underneath.