(often in the plural) A relative by marriage (or through affinity). / Sometimes specifically a parent-in-law of one's child, for which the dedicated terms co-mother-in-law, co-father-in-law are rare.

The mother of one's spouse. / A mother-in-law apartment. / A mother-in-law sandwich. / (dated) A stepmother.

The husband of one's child.

The wife of one's child.

One's spouse's father. / (dated) A stepfather.

The sister of one's spouse. / The wife of one's sibling. / The wife of the sibling of one's spouse. / The sister of the spouse of one's sibling.

Abbreviation of Indiana, a state of the United States of America.

(biochemistry) Abbreviation of integrase. / internegative; a type of film stock, most commonly used regarding 35mm motion picture negative

The brother of one's spouse. / The husband of one's sibling. / The husband of the sibling of one's spouse. / The brother of the spouse of one's sibling.

Supreme commander of the armed forces of an entire country.