Archaic term for a ship's pilot or navigator, used historically. In modern Japanese, 水先案内人 or パイロット are more common.
Anjin is a word used in the early Edo period to refer to a ship's pilot.
The term 按針 (anjin) is of uncertain origin; it may be related to the Chinese characters 按 (to press, to check) and 針 (needle, compass), suggesting a person who checks the compass. It was notably used as the Japanese name of William Adams, an English navigator who served the Tokugawa shogunate.