complementary set; complement
Rare mathematical term for the complement of a set. The more common term is 補集合 (ほしゅうごう).
See also: 補集合
In mathematical literature, 補集合 is used more often than 余集合.
Compound of 余 (よ, 'surplus, remainder') and 集合 (しゅうごう, 'set'), literally 'remainder set'. The exact historical derivation is uncertain; it is a rare alternative to the standard mathematical term 補集合.