actuary comes from Latin actuarius ('keeper of accounts, clerk'), from actus ('a doing, public business'), from agere ('to do, drive'). The modern insurance sense developed in the 19th century. The path is chiefly one of transmission: an older form is taken into English, with the word's shape and meaning carried through the language names and forms preserved in the history. In modern use, the noun sense is "a statistician who calculates insurance risks and premiums", which keeps the etymology connected to the word's present dictionary value rather than treating it as a merely historical label. The wider word family includes related English forms such as act, action and derivatives such as actuarial, showing how the same base continues to support neighboring English vocabulary. The principal historical forms in the chain include Latin actuarius, Latin agere, which anchor the explanation in named linguistic material.