isesti

Isesti is a Finnish derivational suffix used to form adverbs of manner from adjectives, roughly equivalent to the English -ly. It is most productive in adjectives of the forms -inen or -ellinen and is commonly found in formal, scientific, and written Finnish.

Formation and examples

The suffix is typically attached to adjectives ending in -inen or -ellinen after removing that ending, producing adverbs such as turvallisesti (safely) from turvallinen (safe), tieteellisesti (scientifically) from tieteellinen (scientific), and periaatteellisesti (in principle) from periaatteellinen (principled). In practice, the base may undergo minor spelling adjustments to preserve natural Finnish phonology, but the general pattern is to convert the -inen/-ellinen adjective into an adverb with -isesti.

Usage and register

Isesti is especially common in academic, technical, and formal prose, where precise description of manner or evaluation is required. It can convey a sense of thoroughness or emphasis on the mode of action, aligning with other adverbial forms in Finnish. In everyday speech, speakers may rely on more general adverbs formed with other suffixes, such as -asti or -sti, depending on the adjective.

Relation to other suffixes

Finnish also uses adverbial suffixes such as -sti and -asti. The choice among these suffixes depends on the morphological class of the adjective and lexical tradition rather than a fixed rule of meaning. Isesti often contrasts with these by demonstrating its specific use with -inen and -ellinen adjectives, producing adverbs that are common in technical and scholarly language.

See also

Finnish grammar; adverbial suffixes; Finnish morphology.