mother-in-law

/ˈmʌ.ðəɹ.ɪnˌlɔː/

//ˈmʌ.ðəɹ.ɪnˌlɔː// noun

"mother-in-law" is a 11-letter English headword indexed on PlainSpell.

The verdict

“mother-in-law” is outside the top-ranked English vocabulary, used as a noun - the kind of word writers most often double-check.

Unranked
below top-frequency English
13
letters

According to Wiktionary data (CC BY-SA, analyzed May 6, 2026) - The mother of one's spouse.

Key facts for mother-in-law
PropertyValue
Headwordmother-in-law
LanguageEnglish
Part of speechNoun
IPA/ˈmʌ.ðəɹ.ɪnˌlɔː/
Letters13
Misspellings tracked0
Confusable pairs0
SourceWiktionary (kaikki.org)

Where “mother-in-law” sits in English frequency

mother-in-law falls outside the top-100,000 ranked English words, the long-tail zone of technical, archaic, or low-frequency vocabulary, exactly where readers second-guess spellings most.

Beyond rank #100,000. Source: FrequencyWords open word-frequency list.

Spelling & Dictionary Insight

The English entry for mother-in-law is 13 letters long, classified as a noun, and transcribed in the International Phonetic Alphabet as /ˈmʌ.ðəɹ.ɪnˌlɔː/. It sits outside the most-frequent rank tiers, which is often why uncommon words generate more spelling variants per reader. Wiktionary records 5 distinct senses for this headword, so context determines which meaning a reader should apply.

Zero misspellings are on record for mother-in-law in our index, a sign its spelling follows regular English conventions. It is not paired with a close-neighbour confusable in our dataset, since no other headword is close enough in sound or shape to pair with it.

Etymologically, the entry records: From Middle English moder in lawe; equivalent to mother + -in-law. The correct English form is mother-in-law, spelled M-O-T-H-E-R---I-N---L-A-W.

Definition

  1. 1
    The mother of one's spouse.
  2. 2
    A mother-in-law apartment.
  3. 3
    A mother-in-law sandwich.
  4. 4
    A stepmother.
  5. 5
    A spicy Caribbean sauce made with peppers, carrots, onions, lime juice, etc.

Etymology

From Middle English moder in lawe; equivalent to mother + -in-law.

Synonyms

This word in other languages

Definitions, pronunciation, and etymology for this entry are drawn from Wiktionary via the kaikki.org structured extract (CC BY-SA). See the methodology for how each field is sourced and updated.

Frequently Asked Questions

How do you spell "mother-in-law"?
"mother-in-law" is spelled M-O-T-H-E-R---I-N---L-A-W. The IPA pronunciation is /ˈmʌ.ðəɹ.ɪnˌlɔː/.
What does "mother-in-law" mean?
As a noun, "mother-in-law" means: The mother of one's spouse.
How do you pronounce "mother-in-law"?
The IPA (International Phonetic Alphabet) transcription for "mother-in-law" is /ˈmʌ.ðəɹ.ɪnˌlɔː/. Click the speaker icon on the pronunciation badge above to hear it spoken aloud where audio is available.
What is the origin of the word "mother-in-law"?
From Middle English moder in lawe; equivalent to mother + -in-law. See the full etymology section above for more details.
Is PlainSpell free to use?
Yes, PlainSpell is a completely free word reference. You can look up definitions, pronunciations, confusable pairs, homophones, and spelling corrections across 5 languages without any sign-up or subscription.

Using “mother-in-law”

The practical upshot for anyone who landed here from a spell-check.

  • The one correct English spelling is M-O-T-H-E-R---I-N---L-A-W - every other letter order is a misspelling in standard orthography.
  • Say it as /ˈmʌ.ðəɹ.ɪnˌlɔː/ (IPA); tap the speaker on the pronunciation badge to hear it where audio exists.
  • Browse more English words and confusable pairs in the same reference. English words
Data Source

Wiktionary (via kaikki.org), licensed under CC BY-SA & GFDL. Word ordering uses an open word-frequency list; misspelling variants are generated by edit-distance from the correct headword.

Source: Wiktionary (via kaikki.org) Structured Wiktionary extract

Source: FrequencyWords open word-frequency list FrequencyWords open word-frequency list