- parameterA value kept constant during an experiment, equation, calculation, or similar, but varied over other versions of the experiment, equation, calculation, etc.
- para-beside, alongside
- paracosmA detailed imaginary world, especially one created by a child.
- pareidoliaThe tendency to interpret a vague stimulus as something known to the observer, such as interpreting marks on Mars as canals, seeing shapes in clouds, or hearing hidden messages in music.