dense

The word 'dense' entered English in the late 16th century, directly from the Latin adjective densus, which carried the core meanings of "thick, crowded, or compact." This Latin term is of uncertain deeper origin, though it may be related to a Proto-Indo-European root meaning "to be firm or solid." The semantic journey from the physical concept of material thickness to abstract applications is logical and clear. The literal sense of a dense forest or fog (where elements are packed tightly) naturally extended to describe dense writing (where information is packed tightly) and, metaphorically, a dense person (whose thoughts are perceived as impenetrably thick or slow).

The entire word 'dense' is a simplex morpheme. It is a borrowing from Latin densus meaning "thick, close, compact." It functions as a root adjective in English.