centum

Centum is a Latin noun and adjective meaning one hundred. In English it appears in the names of measures and counts formed from the number 100, such as century (100 years), centimeter (one hundredth of a meter), and percent (per hundred). The symbol C denotes 100 in Roman numerals.

In historical linguistics, centum and satem refer to a traditional division of the Indo-European language family based on how the proto-phoneme series known as dorsal consonants developed. The centum group, from centum, includes Latin, Greek, the other Italic, Celtic, and Germanic branches, and is characterized by merging dorsal consonants with velars. The satem group includes Indo-Iranian, Balto-Slavic, Armenian, and some other branches, and is characterized by a sibilant reflex in the word for hundred. The division is a convenience for describing patterns of sound change and is not a strict boundary; some languages have features of both groups or are differently classified by scholars. Tocharian is commonly treated as centum in many schemes, though classifications vary.

The term centum is mostly encountered in historical linguistics and etymology, while in everyday usage it remains a numeric root in many words.