What is the meaning of Direct_limit?

A set of equivalence classes which partition the disjoint union of the members of a direct system; each equivalence class being a sort of “drainage basin” of the mappings (of the morphisms) of the direct system, if these are analogically considered as “rivers”. (If in the indexing poset, then there exist and . If such that then . If k = j then .)

a colimit

Source: wiktionary.org