mother in law definition

Mother-in-law – the woman who becomes your husband’s or wife’s mother after marriage. In English, the term is widely used in family introductions, relationship discussions, and everyday social conversations. A “mother-in-law” is often portrayed as a memorable figure in movies, books, and humor because relationships with in-laws are a common topic across many cultures.

Part of speech:
Noun (singular countable)
Phonetic transcription (IPA):
/ˈmʌð.ɚ.ɪn.lɑː/
CEFR level:
B1
Word frequency:

Pronunciation & Spoken Tips for “Mother-in-law”

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Stress is placed on the first syllable: MU-ther-in-law. The letter combination th is pronounced /ð/, as in the words “the” or “other.” Therefore, do not pronounce it like a d because it happens all the time, regardless of what language people speak. In casual British English, speakers often shorten it with a fast, unstressed middle: /ˈmʌðr.ɪn.lɔː/.

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“Mother-in-law”: Different Forms

This is the only grammar point that makes this word unique. Make a mistake here and it will be obvious. “Mother-in-law” is part of an exclusive set of English nouns that have their plurals attached to the stem word and not at the end of the entire compound.

Learners tend to put the “s” at the end automatically, which is incorrect. Learn this chart by heart once and you will never forget it.

Form

Example

Singular: mother-in-law

  His mother-in-law arrives tomorrow.

Correct plural: mothers-in-law
  Both of our mothers-in-law met at the family reunion last summer.

Wrong plural: mother-in-laws
  Never written or spoken in standard English.

Singular possessive: mother-in-law’s

  Her mother-in-law’s cooking is legendary in the family.

Plural possessive: mothers-in-law’s

  Both mothers-in-law’s opinions were considered carefully.

With “a”: a mother-in-law

  He has a mother-in-law who lives three hours away.

With “my/your/his”:

  My mother-in-law called twice before breakfast.
mother in law in a sentence

In cases where compound nouns are constructed using such structures as “noun + prepositional phrase” (“mother-in-law,” “brother-in-law,” “sister-in-law”), the pluralization is done on the head noun. In this case, ask yourself, “which is really the person? The answer is the mother – so we add the s to that word.

Collocations: How Native Speakers Talk About “Mother-in-law” 

“Mother-in-law” is a word with lots of social implications in the English language, and this can be seen through its collocations. There is no other subject for which the verb collocation occurs more frequently than with the above word. Learning these collocations is sure to elevate your vocabulary a notch up.

Verb + “mother-in-law collocations”:

  • get along with your mother-in-law –  She genuinely gets along with her mother-in-law, which she admits surprises most people.
  • move in with a mother-in-law –  They decided to move in with his mother-in-law to provide daily support.
  • visit your mother-in-law –  They visit her mother-in-law every other Sunday without exception.
  • stay with your mother-in-law –  They stayed with his mother-in-law for six weeks while the flat was being renovated.
  • clash with a mother-in-law –  She clashes with her mother-in-law over parenting decisions, which puts her husband in an impossible position.

Adjective + “mother-in-law collocations”:

  • overbearing mother-in-law –  His overbearing mother-in-law calls four times a day, regardless of whether there’s anything to say.
  • wonderful/supportive mother-in-law –  She credits her supportive mother-in-law with helping her through the first year of parenthood.
  • friendly mother-in-law –
     My friendly mother-in-law made me feel welcome immediately. 

Real Sentences: “Mother-in-law” in Context 

Words out of context are simply that – a list. Look at these examples in three different registers, and note the change in tone from intimate and friendly in family discourse to objective and factual in legal or business dealings, and even dry in informal discourse where the word has a connotation of insider knowledge.

Family Life & Relationships 

  Her mother-in-law offered to babysit every Friday, a gesture that transformed their ability to have any kind of social life whatsoever.
  Setting boundaries with a mother-in-law who means well but oversteps is one of the most common relationship challenges couples face in the first few years.
  He had never expected to become so close to his mother-in-law, as if she were his second mother.

Legal, Housing & Formal Contexts 

  The property was left jointly to her husband and his mother-in-law under the terms of the original deed.
  Many architects now design homes with a dedicated “mother-in-law suite”: a self-contained unit attached to the main house, allowing for proximity without loss of privacy.
  The insurance policy listed his mother-in-law as a named driver, which complicated the claim considerably.

Casual Conversation & Everyday Use 

  My mother-in-law used to have her own key to our apartment, but we eventually decided to set a few clearer boundaries for privacy.
  He asked for his mother-in-law’s recipe for three years before she finally handed over something that turned out to be missing at least two ingredients.
  Spending two weeks at her mother-in-law’s house over the summer tested everyone’s patience, but the children absolutely loved every second of it.

“Mother-in-law” in Spanish, French, and German 

Discover how to properly spell and pronounce this word in other European languages, listen to the translations and repeat them.

Language Word for “Mother-in-Law” Notes
Flag Spanish Spanish   Suegra  From Latin “socrus”. Entirely its own root, no "in-law" phrasing.
Flag French French   Belle-mère  Literally "beautiful mother." The same root as "belle" in English.
Flag German German   Schwiegermutter  "Schwieger" = in-law (from Old High German). "Mutter" = mother.