täyellistä

Täyellistä is not a standard base form in Finnish; it is commonly treated as a misspelling or nonstandard inflection of the adjective täyellinen. The correct partitive singular form of täyellinen is täydellistä. The adjective itself means complete, full, or thorough and is built from the stem täysi (full) with the suffix -ellinen.

In Finnish, adjectives agree with the noun they modify in number and case. The partitive singular täydellistä is used with a singular noun in the partitive case or in negative constructions. For example: Haluan täydellistä tietoa (I want complete information). In predicative clauses formed with negation, the partitive form is also common: Tämä ei ollut täydellistä (This was not complete).

Related forms include the nominative singular täydellinen (the base form), the plural nominative täydeelliset is not correct; the correct plural forms are täydelliset (nominative plural) and täydellisiä (partitive plural). The adverb meaning “completely” is täydellisesti, and the noun form meaning “completeness” is täydellisyys.

Etymology traces täyellinen to täysi (full) with the productive -ellinen suffix that forms adjectives meaning “relating to being full/complete.” The sequence of related words, including täyte (filling, fullness), täyteyden täydennä (various derivations), reflects the same semantic field of fullness and thoroughness.

Overall, täyellistä is not the standard lexical form; the standard spelling and usage is täydellistä, the partitive singular of täyellinen.