The Word Lords were natives of a reality forty-five billion dimensions to the left of the Time Lords'. They had equivalent power to that of the Time Lords within their own sphere. Their universe was made up of language and communication.
Word Lords had abilities that were fuelled by words, phrases that gave them remarkable powers even in realities where the laws of physics were driven by matter and energy rather than language. The more language - phrases, metaphors, books, television, radio broadcasts - in their environment, the more power the Word Lords possessed.
The Word Lords were physically identical to the Time Lords in that they bore an external resemblance to humans and shared their completely alien physiology. With two hearts, a respiratory bypass system and an internal body temperature of 15 degrees Celsius, they were identical, although the differences between the universes probably influenced some unspecified changes. (AUDIO: The Word Lord)
Word Lords were able to fire weapons inside a TARDIS's state of temporal grace field since they were multi-linguistic entities and the laws of N Space didn't apply to them. They are also immune to physical assault, and ordinary guns.
The Word Lords were founded by All, their equivalent of Rassilon. He created the Hand of All, a synthetic pocket universe that fueled their civilisation, made up of miniature versions of the Hand of All. Their most evil and corrupt member, Nobody No-One was either forcefully banished or fled of his own accord, in essence a fugitive as by the time he matched wits with the Seventh Doctor, he resided in the Doctor's universe, not theirs.
Their equivalent of the TARDIS was the CORDIS, a non physical space/time vessel, which ran on common words and phrases used throughout the multiverse and disguised themselves as such. The chameleon meme was unable to hide the pulses of the CORDIS's engines. Nobody was trapped inside The Hand, which was moved inside the mind of the Doctor, who was nearing his seventh regeneration.
Forging an alliance with his earlier self, the Doctor trapped Nobody back inside the Hand and moved it to the mind of Evelyn Smythe as she drew her terminal breath. The Hand died with Evelyn, as did Nobody and the future of the Word Lords, whose society would soon crumble without the Hand's power. (AUDIO: A Death in the Family)