Vowel tense-lax stress alternations

One complexity of the English stress and vowel system is vowel laxing when suffixes are added, that is, when a long or tense vowel reduces to a lax or short vowel with the addition of certain suffixes. This is part of the Latin stress pattern that English has inherited, and can pose challenges for learners, especially for those at intermediate to advanced levels as they learn more academic English with Latinate word elements.

The affected syllable is often the second from the end (the penultimate syllable, denoted here as "-2"), with a tense (long) vowel. As other Latinate suffixes are added, the syllable is now the third syllable from the end ("-3"). Here the vowel shortens to a lax vowel, e.g.,

Vowel = -2	Vowel = -3
nátion /neiʃən/	nátional /næʃənəl/
móde /mɔʊd/	módule /mɔdyu:l/

The addition of certain additional suffixes, incidentally, can cause the original primary stress to reduce to a secondary stress, e.g.:

nàtionálity

mòdálity

1 Tense – lax or long – short alternations

Note the following tense-lax alternations in word formation. With the addition of new suffixes, the stress shifts, and the tense vowels can become lax when they are three syllables or more from the end of the word. This also happens sometimes with shorter words with the addition of -ic, -id.

1.1 Glided /ei/ - lax /æ/

cave

chaste

exclaim

defame

deprave

grade

grain

grateful

grave

humane

inflame

nation

nature

cavity

chastity

exclamatory

defamatory

depravity

gradual

granular

gratitude

gravity

humanity

inflammatory

national, nationality

natural

navy

opaque

page

pale

placate

profane

rabies

sacred

sane

state

table

vain

vapor

navigate

opacity

paginate

pallid

placid

profanity

rabid

sacrament

sanity

static

tabular

vanity

vapid

1.2 Glided /i:/ - lax /ɛ/

appeal

athlete

austere

brief

clean

clear

compete

concede

convene

creed

diabetes

deceive

discreet

extreme

heal

appellative

athletic

austerity*

brevity

cleanliness

clarity*

competitive

concession

convention

credible

diabetic

deception

discretion

extremity

health

Hellene

hygiene

intervene

meter

obscene

perceive

proceed

recede

receive

repeat

serene

severe

steal

sincere

supreme

Hellenic

hygienic

intervention

metric

obscenity

perception

procession

recession

reception

repetitive

serenity

severity

stealth

sincerity*

supremacy

*Some of these are “r-colored” vowels, /ɛr/, that is, the vowel sound seems somewhat different due to the influence of the /r/.

1.3 Diphthong /ai/ - lax /ɪ/

arthritis

Bible

collide

confide

contrite

crime

cycle

decide

define

dendrite

derive

describe

divide

divine

elide

expedite

juvenile

ignite

inscribe

line

mime

arthritic

biblical

collision

confident

contrition

criminal

cyclical

decision

definitive

dendritic

derivative

description

division

divinity

elision

expedition

juvenility

ignition

inscription

linear

mimic

mine

oblige

parasite

prescribe

prime

pyrite

revise

rite

satire

Semite

senile

sign

saliva

title

transcribe

triune

type

tyrant

vile

wide

wild

mineral

obligatory

parasitic

prescription

primitive

pyritic

revision

ritual

satirical

Semitic

senility

signal

salivate

titular

transcription

trinity

typical

tyranny

vilify

width

wilderness

Also, in British pronunciation of -ile as /ail/, we see alternations like hostile, hostility; futile, futility.

1.4 Glided /ou/ - lax /ɔ/

code

compose

cone

cyclone

episode

evoke

expose

globe

holy

hypnosis

joke

know

locate

microbe

microscope

codify

composite

conic

cyclonic

episodic

evocative

expository

globular

holiday

hypnotic

jocular

knowledge

locative

microbic

microscopic

mode

neurosis

omen

ozone

phone

provoke

psychosis

solo

symbiosis

telephone

telescope

tone

trope

verbose

vocal

modular

neurotic

ominous

ozonic

phonics

provocative

psychotic

solitude

symbiotic

telephonic

telescopic

tonic

tropical

verbosity

vocative

1.5 tense /u:/ - lax /ʊ/

adjudicate

assume

consume

crucify

deduce

duke

induce

numeral

adjudge

assumption

consumption

crux

deduction

duchy

induction

number

presume

produce

punitive

reduce

repugn

resume

seduce

presumption

production

punish

reduction

repugnant

resumption

seduction

2 Other alternations

There is also occasionally destressing of these vowels with the addition of a suffix, such as the negative suffix -in:

famous

finite

potent

infamous

infinite

impotent

A few other such patterns also occur:

pronounce

profound

abstain

maintain

detain

pronunciation

profundity

abstinence, abstention

maintenance

detention

pertain

persevere

retain

saline

pertinent

perseveration

retention

salinity

Possible variations or exceptions: Some speakers vary in whether they shorten these syllables in a few words; this can depend on dialect or personal style.

penalize, phonological, economic, equinox, equatorial, equilateral, equidistant, homophone, hologram, amenable, placable, granary, nascent, predicate, simultaneous, sonorous, ammonic, patronize, patronage, microbic, gnomic, Hellenic, hydrophobic, finitude, homicide, myopic