In mathematical order theory, a **scattered order** is a linear order that contains no densely ordered subset with more than one element (Harzheim 2005:193*ff.*)

A characterization due to Hausdorff states that the class of all scattered orders is the smallest class of linear orders which contains the singleton orders and is closed under well-ordered and reverse well-ordered sums.

Laver's theorem (generalizing Fraïssé's conjecture) states that the embedding relation on the class of countable unions of scattered orders is a well-quasi-order (Harzheim 2005:265).

The order topology of a scattered order is scattered. The converse implication does not hold, as witnessed by the lexicographic order on
Q
×
Z
.