Nature

The Tenth Doctor observed that Richard Lazarus thought he could defy the laws of nature, only for nature to get "her own back". (TV: The Lazarus Experiment)

Part of Paul Magrs' homework in December 1979 was nature-study, so he went down to the Burn to sketch the trees. (PROSE: Party Like it's 1979)

UNIT Staff Sergeant A. Frederick believed a de-emphasis on the "exact nature of threat and potency of clear-up" was necessary during Operation Mannequin. (PROSE: Operation Mannequin)

Historians who had been allowed access to the "Monster Vaults" of the databanks in the Doctor's TARDIS likened the Abzorbaloffs' absorption ability to a bacterium or a tapeworm, all essentially parasitic in nature. (PROSE: The Monster Vault)