Definition 2024





co-mother-in-law (plural co-mothers-in-law)

  1. (uncommon) The mother of one's son- or daughter-in-law; that is, the mother-in-law of one's son or daughter, or, the mother of one spouse in relation to the parents of the other spouse.
    (in the plural) The relationship between women whose children marry each other; the mother of the bride vis-à-vis the mother of the groom.
    • 1901, Honoré de Balzac, (trans.) Francis MacNamara, The Physiology of Marriage, page 334:
      After dinner, the discerning eye of the co-mother-in-law divines the work of darkness. Your wife also is an expectant mother !
    • 1912, Sarah Grand, Adnam's Orchard, page 508–509:
      She had a right of entrée to the Castle now as prospective co-mother-in-law with the duchess, and made the most of it.
    • 1956, Margaret Mead, New lives for old: cultural transformation—Manus, 1928-1953, page 381:
      [] responded with temper and irritability toward her step-daughter, Anna, who was so demure and so complete a member of the new society, and toward Ngaoli, her co-mother-in-law, gaunt, old, married under the old system, a devoted church member, righteous mother of five children, who fortunately had no complications in her life.

Usage notes

  • In conversation, the generic "in-law" is generally used, with context left to disambiguate. Once grandchildren are born, the term co-grandmother may be used if the focus is on the relationship through the grandchildren rather than though the married couple.


Coordinate terms

Related terms