Kattoja

Kattoja is the partitive plural form of the Finnish noun katto, meaning "roof" or "roofing." In Finnish grammar the partitive plural expresses an indefinite or incomplete quantity, ongoing or partial actions, and is used after certain verbs and in negative constructions.

Forms and morphology:

- Nominative singular: katto

- Partitive singular: kattoa

- Nominative plural: katot

- Partitive plural: kattoja

- Genitive plural: kattojen

Usage examples:

- Näen kattoja. (I see roofs.) — indefinite number of roofs observed.

- Hän korjaa kattoja. (He/she repairs roofs.) — ongoing work on some roofs.

- Kaupunki on täynnä vanhoja kattoja. (The city is full of old roofs.)

Contrast with counting and specificity: when counting discrete items Finnish commonly uses the partitive singular after numerals (kaksi kattoa = two roofs), whereas kattoja denotes an unspecified plural quantity. Negative sentences also typically take the partitive: en näe kattoja (I do not see roofs).

The form kattoja illustrates typical Finnish consonant and vowel patterns (the geminate consonant tt and back vowel a), and it functions as a routine example in descriptions of Finnish nominal inflection and partitive usage.