- Pareidolia (/ˌpærɪˈdoʊliə, ˌpɛər-/; also US: /ˌpɛəraɪ-/) is the tendency for perception to impose a meaningful interpretation on a nebulous stimulus, usually visual, so that one sees an object, pattern, or meaning where there is none. It is a type of apophenia.
- Real number (Wikipedia)
In mathematics, a real number is a number that can be used to measure a continuous one-dimensional quantity such as a distance, duration or temperature. Here, continuous means that pairs of values can have arbitrarily small differences. Every real number can be almost uniquely represented by an infinite decimal expansion.