Grammar: Morpheme & Allomorphs

Posted July 4, 2015 by Kathy Davie in Author Resources, Editing, Grammar Explanations, Self-Editing, Writing

Morphemes are another of those background bits of linguistic information you MIGHT want to know about. It is a fancy word for the smallest possible word that is still understood as a whole word: dance, possible, fancy, man, dog, truck, meat, pail, etc.

Naturally, linguists have drilled down even further and divided this lone single unit into different categories: free morphemes, bound morphemes, and unique morphemes, which themselves are divided into subcategories.

A morpheme and a free morpheme are the same thing. A bound morpheme simply means it’s not a standalone word. A unique morpheme is similar to the bound form, but it imparts a very specific meaning to its root word. And let’s not forget the allomorphs.

There is no easy (or sensible) definition for an allomorph, as it is so many different things. I’m surprised that linguists haven’t come up with more, and in some cases, better terms and more categories. The easiest explanation for the allomorph is anything that changes a morpheme.

Grammar Explanations is…

…an evolving list of the structural rules and principles that determines where words are placed in phrases or sentences as well as how the language is spoken. Sometimes I run across an example that helps explain better or another “also known as”. Heck, there’s always a better way to explain it, so if it makes quicker and/or better sense, I would appreciate suggestions and comments from anyone… Are there areas of grammar with which you struggle? If you’d like to track it, bookmark this page and consider sharing this Grammar Explanation with friends by tweeting it.

Morphemes and Allomorphs

A Morpheme is…

Definition: The smallest unit of a word that is still a word.

An Allomorph is…

Definition: A variant form of a morpheme that can refer to affixes, word endings, or adjacent word choices, and can change the sound of the word although the changes do not change the meaning of the word. It can include creating a plural, tenses, choice of article, and more.

A.k.a., morphemic variant, morphemic

Deconstruction of a Morpheme
Three Types of Morphemes:

Deconstruction of an Allomorph
Three Types of Allomorphs:

Deconstruction of a Morpheme
It’s easiest to explain what a morpheme is by breaking words down.
Structure of a Morpheme
Affix Definition: A morpheme that comes at the beginning (prefix) or end (suffix) of a base morpheme.

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Most are one morpheme, one syllable:

  • pre-
  • -s
  • -ing
  • in-
Base Definition: A morpheme that gives a word its meaning.

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Dog is a base morpheme and gives the word dogs its meaning: a particular type of animal.
Examples of the Structure
dog one morpheme, one syllable
dogs two morphemes, one syllable – dog + s (The s is also a plural marker on the noun.)
technique one morpheme, two syllables

Even though the word has two syllables, it is a single morpheme because it cannot be broken down into smaller meaningful parts.


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three morphemes – un- + lady + -like,
four syllables – un- + la + dy + -like

None of these morphemes can be broken up any more without losing all sense of meaning: lady cannot be broken up into la and dy, even though they are separate syllables.

Note that each syllable has no meaning on its own.

Types of Morphemes
Free Morpheme Definition: A morpheme that can stand alone and cannot be divided into smaller word units. A good test McIntyre suggests is if the word can stand alone as the answer to a question, it’s a free morpheme.

A.k.a., unbound morpheme, free form, free-standing morpheme, free root,

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Breakdown of a Morpheme
Free Morpheme Free + Bound Morpheme
Content Word Definition: A word that conveys information in a text or speech that conveys an idea to someone else. Typical content words include nouns, verbs, adjectives, and adverbs.

A.k.a., lexical word, open

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Function Word Definition: Performs some kind of grammatical role and carries little meaning of their own. They are only understood when combined with other words in a sentence.

A.k.a., grammatical word, closed

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Bound Morpheme Definition: A morpheme that appears only as part of a larger word or that occurs in only one phrase. For a bound morpheme to make sense, you have to add another morpheme.

Prefixes and suffixes are bound root morphemes.

A.k.a., bound form, bound root morphemes, bound root,

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Bound Morpheme Morpheme Bound Morpheme Morpheme
-ed sailed -ing singing
-est lightest -ly motherly
-er girder -s houses
funct defunct
Derivational Morpheme Definition: Modifies a word by forming a new word out of old words.

Prefixes simply make a new noun out of a noun while suffixes are generally added to a verb or adjective to form a noun.

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Derivational Prefix
Definition: When a prefix is added to a noun, it supposedly forms a new noun with a different meaning.
Prefix Morpheme Becomes
ex- term (noun) exterminate (verb)
im- peach (noun, verb) impeach (verb)
out- patient (noun) outpatient (noun)
re- trial (noun, verb) retrial (noun)
sub- group (noun, verb) subgroup (noun)
un- nerve (noun) unnerve (verb)
Derivational Suffix
Definition: Suffixes are generally added to a verb or adjective to form a noun with a different meaning and changing the part of speech as well.
Suffix Morpheme Becomes
-able solve (verb) solvable (adjective)
-er arch (adjective, noun, verb) archer (noun)
-ish style (noun) stylish (adjective)
-ous courage (noun) courageous (adjective)
-y fizz (noun, verb) fizzy (adjective)
Inflectional Morpheme Definition: Modifies a word to fit its role in a sentence — conjugation and declension — without changing its underlying meaning. This can be done through tense, number, possession, or comparison

Be aware that some suffixes can perform in either derivational or inflectional.

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Inflectional Morpheme
(Prefix or Suffix)
Morpheme Becomes Part of Grammar
-s flower flowers plural
-es teach teaches 3rd person present
‘s Ann Ann’s possessive, singular
s’ girls girls’ possessive, plural
-ed book booked past tense
-en dead deaden new word
-er teach teacher noun, person
-est black blackest comparison
-ing bait baiting gerund, present participle
Unique Morpheme Definition: Resembles bound morphemes because they cannot stand alone and mean something, but they still contribute meaning to a word.

Another name for the unique morpheme is cranberry morph because the cran provides a “unique” explanation for the unique morpheme. While not a free morpheme, cran is considered a root because of its similarity to the roots in black-berry, blue-berry, snow-berry, or wax-berry. Cran differentiates the (cran)berry from any others.

a.k.a., cranberry morph, cranberry word, blocked morpheme, bound root, leftover morpheme

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Unique Resulting Unique Resulting
-ter laughter -ept inept
mul- mulberry -kempt unkempt
luke- lukewarm -ane inane
-ert inert -teen umpteen
-gruntled disgruntled aff- affable
Deconstruction of an Allomorph
It’s easiest to explain an allomorph by dissecting it.
Structure of an Allomorph
Morpheme With Allomorph Morpheme With Allomorph
ceive con-ceive
em em-bitter
cept con-cept
en en-chain
duke duke-dom
Types of Allomorphs
Phonologically Conditioned Allomorphy Definition: Sound-based allomorphs which includes indefinite articles and additive allomorphs.

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Basic Word Ending Sounds
Morpheme Allomorph Sounds Like… Morpheme Allomorph Sounds Like…
awesome -zm fished
boxes -zz grabbed -d
busses -iz hats -s
cats -s wanted əd
Rule: Whether a or an is the allomorph chosen depends on how an adjacent morpheme is pronounced.
Indefinite Article Allomorphs
a dog
a flower
a window
an eagle
an inch
an Oscar
Additive Allomorph Rule: Adding an affix changes the tense or creates a positive or negative impression, and the word sound may change.

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Regular Past Tense Morphemes Negative Prefixes
Sounds like id after d or t:

  • defeated
  • heated
  • threaded
  • waded

Sounds like t after all other voiceless sounds:

  • hissed
  • picked
  • ripped

Sounds like d after all other voiced sounds:

  • fizzed
  • howled
  • measured
  • wedged
Sounds like il before l:

  • illegal
  • illegible

Sounds like im before bilabial sounds:

  • immature
  • impossible

Sounds like in elsewhere:

  • ineligible
  • inexpensive
  • independent

Sounds like un elsewhere:

  • unassailable
Morphologically Conditioned Allomorphy Rule: Structure-based allomorphs. This is typical of English in that there is no one-size-fits-all rule.

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assume assumption assumptive assumable
consume consumption consumptive consumable
presume presumption presumptuous presumable
resume resumption resumptive resumable
subsume subsumption subsumptive subsumable
-ally an-throp-olog-ic-ally
-ly ac-cid-ent-ly
Lexically Conditioned Allomorphy Definition: Forms a plural for nouns using a simple plural of -s or -es, the replacive, or zero allomorphs. It’s also about the formation of different verb tenses — suppletion allomorphs.

Caution: The choice of allomorph is unpredictable and must be memorized on a word-by-word basis.

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Simple Plural uses -s or -es
girl girls box boxes
school schools minus minuses
flower flowers fox foxes
plane planes wrench wrenches
Replacive Allomorph Definition: Replaces letters within the word to create plurals using -en, irregular plurals, or past tense forms.

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-en Plurals
brother brethren
child children
man men
woman women
ox oxen
Noun-Verb Replacives
Definition: A rare type of replacive morpheme which distinguishes nouns from verbs.
Noun Verb Noun Verb
advice advise sheath sheathe
bath bathe shelf shelve
grief grieve strife strive
half halve teeth teethe
safe save thief thieve
serf serve wreath wreathe
Irregular Plurals
foot feet goose geese
mouse mice tooth teeth
criterion criteria
stratum strata
Irregular Past Tenses
swim swam swum
drink drank drunk
sing sang sung
bring brought
take took taken
break broke broken
Zero Allomorph Definition: There is no change from singular to plural.

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deer moose
fish sheep
Suppletion Definition: Allomorphs of a morpheme are phonologically unrelated and changes the shape of the word.

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be am are is was been
go goes went gone
good better best
one first
bad worse worst

For even more fun — and an exhaustive collection of English affixes — see Michael Quinion’s Affixes: The Building Blocks of English, based on his book Ologies and Isms: Word Beginnings and Endings (2002).

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