1   Introduction

The plural stem is used to form the plural of the translative, inessive, elative, adessive, ablative, allative, abessive, and instructive.

2   Formation

The plural stem is formed with the aid of the genitive stem. The plural stem always includes a plural marker i. In the inflection examples below, the inessive endings have been separated from the stem by a hyphen. A good knowledge of consonant gradation and vowel change i ~ e is of great use.

2.1   Words that end in a vowel

a) Words that end in a single a

If a word ends in a single a, there are two ways of forming the plural stem. If a word includes two syllables, and there is o or u in the first one, the plural stem is formed by replacing the a by the plural marker i.

Nominative	Inessive sg	Inessive pl	Translation
kova	kova-ssa	kovi-ssa	hard
muna	muna-ssa	muni-ssa	egg
loota	looda-ssa	loodi-ssa	box
luuta	luuda-ssa	luudi-ssa	broom
koira	koira-ssa	koiri-ssa	dog
kuiva	kuiva-ssa	kuivi-ssa	dry
routa	rouda-ssa	roudi-ssa	frost
juoma	juoma-ssa	juomi-ssa	drink

Otherwise, the last letter a of the genitive stem is replaced by o, and the plural marker i is attached after it.

Nominative	Inessive sg	Inessive pl	Translation
kana	kana-ssa	kanoi-ssa	hen
vaaka	vaa'a-ssa	vaaoi-ssa	scale
helma	helma-ssa	helmoi-ssa	hem
Veera	Veera-ssa	Veeroi-ssa	Veera
ripa	riva-ssa	rivoi-ssa	handle
hiiva	hiiva-ssa	hiivoi-ssa	yeast
laiva	laiva-ssa	laivoi-ssa	ship
kauppa	kaupa-ssa	kaupoi-ssa	shop
keila	keila-ssa	keiloi-ssa	bowling pin
leuka	leua-ssa	leuoi-ssa	chin
hiekka	hieka-ssa	hiekoi-ssa	sand
tiukka	tiuka-ssa	tiukoi-ssa	tight

The previous rule is also applied to all words with three or more syllables no matter which vowels there are in the preceding syllables.

Nominative	Inessive sg	Inessive pl	Translation
mansikka	mansika-ssa	mansikoi-ssa	strawberry
mustikka	mustika-ssa	mustikoi-ssa	blueberry

b) Words that end in a single ä

If a word ends in a single ä, the plural stem is formed by replacing ä by the plural marker i.

Nominative	Inessive sg	Inessive pl	Translation
väärä	väärä-ssä	vääri-ssä	wrong
räkä	rää-ssä	räi-ssä	snot

c) Words that end in i

If a word ends in a single i, and it does not undergo the vowel change i ~ e, the plural stem is formed by replacing the i by e and adding the plural marker i after it.

Nominative	Inessive sg	Inessive pl	Translation
kiivi	kiivi-ssä	kiivei-ssä	kiwi fruit
kahvi	kahvi-ssa	kahvei-ssa	coffee
kaappi	kaapi-ssa	kaapei-ssa	cabinet

If a word undergoes the vowel change i ~ e, the plural stem is formed by replacing the last letter e of the genitive stem by the plural marker i, except for the words ending in -si.

Nominative	Inessive sg	Inessive pl	Translation
kieli	kiele-ssä	kieli-ssä	language
koipi	koive-ssa	koivi-ssa	leg
mäki	mäe-ssä	mäi-ssä	hill

If a word ends in -si and undergoes the vowel change i ~ e, the plural stem is similar to the nominative stem.

Nominative	Inessive sg	Inessive pl	Translation
vesi	vede-ssä	vesi-ssä	water
kansi	kanne-ssa	kansi-ssa	lid
jälsi	jälle-ssä	jälsi-ssä	cambium
virsi	virre-ssä	virsi-ssä	hymn

d) Words that end in a single e, o, u, y, or ö

If a word ends in a single e, o, u, y, or ö, the plural stem is formed by adding the plural marker i to the genitive stem.

Nominative	Inessive sg	Inessive pl	Translation
nalle	nalle-ssa	nallei-ssa	teddy bear
aatto	aato-ssa	aatoi-ssa	eve
koulu	koulu-ssa	koului-ssa	school
pyry	pyry-ssä	pyryi-ssä	snowstorm
säilö	säilö-ssä	säilöi-ssä	storage

e) Words that end in a long vowel

If a word ends in a long vowel, the plural stem is formed by replacing the last letter of the genitive stem by the plural marker i.

Nominative	Inessive sg	Inessive pl	Translation
maa	maa-ssa	mai-ssa	country
tee	tee-ssä	tei-ssä	tea
ehtoo	ehtoo-ssa	ehtoi-ssa	evening
puu	puu-ssa	pui-ssa	tree
pyy	pyy-ssä	pyi-ssä	hazelhen
pää	pää-ssä	päi-ssä	head

f) Words that end in a diphthong that ends in i

If a word ends in a diphthong that ends in i, the plural stem is formed by replacing the i by the plural marker i. Thus, the plural stem is similar to the nominative and genitive stem.

Nominative	Inessive sg	Inessive pl	Translation
hai	hai-ssa	hai-ssa	shark
koi	koi-ssa	koi-ssa	moth

f) Word ends in ie, uo, or yö

If a one-syllable word ends in the diphthong ie, uo, or yö, the plural stem is formed by omitting the first component of the diphthong, and adding the plural marker i.

Nominative	Inessive sg	Inessive pl	Translation
tie	tie-ssä	tei-ssä	road
suo	suo-ssa	soi-ssa	marsh
työ	työ-ssä	töi-ssä	work

f) Words that end in another diphthong or a vowel cluster

If a word ends in another diphthong or a vowel cluster that is not a diphthong, the plural stem is formed by adding the plural marker i to the genitive stem. This rule also applies to polysyllabic words that end in -ie, -uo, or -yö.

Nominative	Inessive sg	Inessive pl	Translation
neliö	neliö-ssä	neliöi-ssä	square
kolmio	kolmio-ssa	kolmioi-ssa	triangle
collie	collie-ssa	colliei-ssa	collie

2.2   Words that end in a consonant

If a word ends in a consonant or a relic consonant, the plural stem is formed from the genitive stem. In the inflection examples below, the inessive endings have been separated from the stem by a hyphen.

a) Genitive stem ends in -de

If the genitive stem ends in -de, in front of which there is a vowel, the plural stem is formed by replacing the de by ksi. This group includes words whose nominative stem ends in -s.

Nominative	Inessive sg	Inessive pl	Translation
osuus	osuude-ssa	osuuksi-ssa	share, part
kauneus	kauneude-ssa	kauneuksi-ssa	beauty
rakkaus	rakkaude-ssa	rakkauksi-ssa	love
teollisuus	teollisuude-ssa	teollisuuksi-ssa	industry
hyvyys	hyvyyde-ssä	hyvyyksi-ssä	goodness

b) Genitive stem ends in -nne

If the genitive stem ends in -nne, the plural stem is formed by replacing the nne by nsi. This group includes words whose nominative stem ends in -s or -t.

Nominative	Inessive sg	Inessive pl	Translation
kolmas	kolmanne-ssa	kolmansi-ssa	the third
neljäs	neljänne-ssä	neljänsi-ssä	the fourth
tuhannes	tuhannenne-ssa	tuhannensi-ssa	the thousandth
mones	monenne-ssa	monensi-ssa
tuhat	tuhanne-ssa	tuhansi-ssa	thousand

c) Other words

The plural stem of other words, which end in a consonant or a relic consonant, is formed by replacing the last letter of the genitive stem by the plural marker i. This group does not include new loan words.

Nominative	Inessive sg	Inessive pl	Translation
vene	venee-ssä	venei-ssä	boat
laite	laittee-ssa	laittei-ssa	device
koe	kokee-ssa	kokei-ssa	test
avain	avaime-ssa	avaimi-ssa	key
sydän	sydäme-ssa	sydämi-ssä	heart
tytär	tyttäre-ssä	tyttäri-ssä	daughter
sisar	sisare-ssa	sisari-ssa	sister
karvas	karvaa-ssa	karvai-ssa	bitter
kaunis	kaunii-ssa	kaunii-ssa	nice
paras	parhaa-ssa	parhai-ssa	the best
kiuas	kiukaa-ssa	kiukai-ssa	sauna heater
varis	varikse-ssa	variksi-ssa	crow
ohut	ohue-ssa	ohui-ssa	thin
neitsyt	neitsye-ssä	neitsyi-ssä	virgin
sävel	sävele-ssä	säveli-ssä	note, melody
askel	askele-ssa	askeli-ssa	step
askel	askelee-ssa	askelei-ssa	step

d) New loan words

The plural stem of new loan words that end in a consonant is formed by replacing the last i of the genitive stem by e and adding the plural marker i after it.

Nominative	Inessive sg	Inessive pl	Translation
stadion	stadioni-ssa	stadionei-ssa	stadium
radar	radari-ssa	radarei-ssa	radar

3   Usage

The plural stem is used to form the plural of the translative, inessive, elative, adessive, ablative, allative, abessive, and instructive. The following example shows, how case endings are attached to the plural stem.

Case	Word	Translation
Nominative	jalka	foot
Translative pl	jaloiksi	becoming the feet
Inessive pl	jaloissa	in the feet
Elative pl	jaloista	out of the feet
Adessive pl	jaloilla	on the feet
Ablative pl	jaloilta	from the feet
Allative pl	jaloille	onto the feet
Abessive pl	jaloitta	without the feet
Instructive pl	jaloin	with the feet