Word

You may be looking for the computer program.

Words were the basis of Carrionite science. Part of language, the choosing of one's words was an essential part of what made one a great poet or playwright, and thus the Tenth Doctor held that William Shakespeare's ability to always find the right words was part of what made him such a "genius". (TV: The Shakespeare Code)

The first Dalek whom open fired upon Davros claimed to have no understanding of the word pity, it not being registered in his vocabulary bank. (TV: Genesis of the Daleks)

Other references

Conversations could be refered to as "a word", especially when one requested to speak with another. (TV: Boom Town, Love & Monsters)