Intercalation (geology), a special form of interbedding, where two distinct depositional environments in close spatial proximity migrate back and forth across the border zone
Intercalary chapter, a chapter in a novel that does not further the plot. See also frame story (sometimes called intercalation).
In biology:
Intercalary segment, an appendage-less segment in the segmental composition of the heads of insects and Myriapoda
Intercalation (biochemistry), process discovered by Leonard Lerman by which certain drugs and mutagens insert themselves between base pairs of DNA
