þihtaz

þihtaz is a reconstructed Proto-Germanic word believed to mean "thick" or "dense." Its exact meaning is inferred from its cognates in descendant Germanic languages. In Old English, the related word þicce can mean "thick," "dense," or "frequent." In Old Norse, the word þéttr has similar meanings, referring to something compact or dense. In Gothic, the word þalath could also relate to thickness.

The Proto-Germanic root is thought to be *þiht-, and the reconstruction of *þihtaz is based on comparative linguistics. It is an adjective that would have described a physical quality. The precise phonetic reconstruction and the precise semantic range are subjects of ongoing scholarly debate among historical linguists.

The word likely influenced the development of various terms related to density and thickness across different Germanic languages. While *þihtaz itself is not directly attested in any surviving texts, its presence is a crucial element in understanding the vocabulary of Proto-Germanic and the evolution of Germanic languages. The concept it represents is fundamental and has persisted in the lexicons of languages like English (thick), German (dick), and Dutch (dik).