Indeclinable words

Finnish is the language of declinations, meaning that words change quite a bit from their basic form when you use them in a sentence. There are exceptions to this though: some words never appear in any case. They are just in their basic form, no matter what the words around it do.

Examples:
Pikku siskolla on nukke.
Viime vuonna muutin Helsinkiin.
Ensi viikolla matkustan Thaimaahan.

Finnish English
viime last
ensi next
melkein almost
pikku little
eri different
koko the whole
hyvin very, well
oikein correct, correctly
väärin wrong, wrongly
samoin same
auki open
irti loose
kiinni closed
poikki broken
puhki through
rikki broken
sekaisin mixed