istiisesti
Istiisesti is a term with very limited attestation in Finnish-language sources. It is not listed in standard dictionaries, and there is no established, widely accepted definition. In most reference works, istiisesti is treated as either a misspelling, a nonce coinage, or a regional/fictional usage rather than a recognized Finnish word.
In terms of morphology, istiisesti would resemble other Finnish adverbs formed with the suffix -isesti, which
Possible interpretations in informal use include: as a deliberate neologism to denote a certain manner or style
If encountered in writing, istiisesti should be treated with caution: it is not part of standard Finnish
See also: Finnish language, morphology, adverbs of manner, -isesti suffix.