-si-
See also: Appendix:Variations of "si"
Finnish
Etymology
Originally from the plural stem of -nen.
Interfix
-si-
- Used in adverbs between a noun (usually referring to an article of clothing) and an external location case ending (adessive, allative, ablative) to refer to a state where one is (only) wearing that clothing. The interfix is placed right before the case ending.
- Used in adverbs between a noun and an external location case ending with a more generic diminutive meaning. The interfix is placed right before the case ending.
Usage notes
It is basically arbitrary whether the interfix attaches to the singular or plural stem of any given word, but it does appear to always be attached to the strong stem for nouns that have gradation. Even further, in some cases it is preceded by an unetymological -i-, probably extracted by analogy from actually regular plural stems. The nominal form obtained as a result of attaching the locative case ending is considered to be in plural.
Only cases where the corresponding -nen derivative does not exist as an independent noun can be considered to use the -si- interfix, which has developed from the inflected forms of those derivatives by analogy.
Derived terms
Finnish terms interfixed with -si-