kompleksaj
Kompleksaj is the plural adjective form in Esperanto meaning “complex” when describing plural nouns. In Esperanto, adjectives are declined for number but not for gender; the plural is marked by adding -j to the adjective. Therefore, the base form kompleksa or kompleksa- (depending on the noun) becomes kompleksaj when used with a plural noun. The word is used to describe things that consist of many interconnected parts or layers, such as ideas, systems, or problems.
In practice, kompleksaj is commonly seen in phrases like kompleksaj problemoj (complex problems) or kompleksaj situacioj
Etymology-wise, kompleksa derives from the root related to the concept of “complex,” a sense carried into Esperanto