1. REPLACIVE MORPHEME (ROOT MODIFICATION)
Replacive morpheme (root modification) : the process of changing the shape of the root itself.
There are two kinds of replacive morpheme (root modification):
Vowel change
Consonant mutation
Vowel Change: The process of changing the vowel in order to express certain morphological categories/process.
Umlaut: vowel changes that result historically from assimilation to front vowels that have since been lost in the language.
Example: foot - feet
tooth - teeth
goose - geese

2. Root modification (cont……)
Ablaut : vowel changes that do not result historically from assimilation to vowels that have since been lost.
Examples:
sing - sang blood – bleed
ring - rang food- feed
hold - held drink - drunk
drink - drank long - length
feel - felt high - height
sleep - slept strong - strenght
keep - kept man- men
buy - bought woman- women
bring - brought mouse- mice

3. Replacive morpheme (cont…..)
Consonant Mutation: the process of replacing one consonant with the other consonants at the beginning or ends of the root in order to express particular morphological categories.
There are three kinds of consonant mutation:
Spirantisation: the changes of initial voiceless stops becomes voiceless fricatives.
p → f
t → z
k → h
Fortition: the changes of initial voiced stops become voiceless stop
b → p
d → t
g → k

4. Root modification (cont……)
Lenition: the changes of voiceless stops undergoing voicing, initial voiced stops become fricatives, and m becomes v.
p → b
t → d
k → g
b → v
d → z
g → h
m → v
The examples of consonant mutation are taken from Breton.

5. Root modification (cont…….)
Possesive Pronoun
Mutation Pattern
Noun
Possessed
Form
ma ‘my’
Spirantisation
penn ‘head’
ma fenn ‘my head’
o ‘ your’
Fortition
bara ‘ bread’
o para ‘your bread’
e ‘his’
e ‘her’
Lenition
tad ‘father’
e dad ‘his father’
e zad ‘her father’

6. SUBTRACTIVE MORPHEMES
Subtractive morphemes are those in which some element of the root is deleted in order to express a particular meaning.
For example:
In Dyrbal, verbs form their imperatives by deleting the final consonant of the verb root.
banij (come) → bani (come!)
balgal (hit) → balga (hit!)
Another language in which we can point the existence of subtractive morpheme is French. The basic forms of adjectives in French are those which are associated with feminine nouns, while masculine forms of adjectives often involve the deletion of the final consonant.
feminine masculine
petite ‘small’ petit ‘small’
laide ‘ugly’ laid ‘ugly’