A
centiare (symbol
ca) is a unit of area, equal to 1
square meter, used in some countries for measuring small land areas, usually in combination with ares, ''e.g.'' 1a 16ca = 116 m². Though its base unit, the
are, was defined by older forms of the
metric system, it is not part of the modern metric system, the
International System (SI). It is accepted, but not encouraged, for use with the SI.