Force-aging is instantly forcing a Norn, Ettin, or Grendel into the next life stage.
Some third-party programs, such as Devthing, the Freylabuttons and BORG, can do this.
In Creatures 3/Docking Station, creatures can also be force-aged via the CAOS Command Line, using the command targ norn ages # ("targ norn" is the selected creature, and "#" is the number of lifestages the creature will be aged; for example, using the command "targ norn ages 4" on a baby Norn will force it to the adult life stage, and vice versa). It is recommended that you use numbers less than 7, unless you want to age your creature to death. In norns with a mutated Life receptor, force-aging can cause the rest of the norn's receptors to kick in, leading to a fast transition between the remaining life stages to death. If you wish to force age a norn, type into the caos command line: targ norn ages (the amount of life stages you want them to go). Force aging is not reversable, so don't accidentally age a norn.
In Creatures 2, baby creatures were force-aged to child if you used a COB or cheat to instantly teach them the entire vocabulary. They also often forgot their name.