A salinometer is an instrument used to measure the salinity of water. There are several synonyms for this word that describe similar devices, including an hydrometer, an oceanographer or salt meter, and a conductivity meter. These instruments work by measuring the density or electrical conductivity of water, which can then be used to determine its salt content. Other related terms include refractometer, which measures the degree of light refraction in a liquid to estimate its salinity, and spectrophotometer, which uses light absorption to determine the salt content of water. While each of these instruments has its own unique properties and uses, they are all designed to help researchers, scientists, and other professionals better understand the composition and properties of seawater and other saline solutions.