pitkäillä

Pitkäillä is a Finnish inflected form of the adjective pitkä, meaning long. It is the adessive plural form used when describing plural nouns in the adessive case, typically to indicate location on or with long things, or more generally in contexts where the described nouns are plural and in that case. As a result, pitkäillä does not carry a separate lexical meaning beyond being a grammatical form.

In Finnish, adjectives decline to agree with the nouns they modify in number and case. The base form pitk- yields several inflected variants, for example: nominative plural pitkät (long ones), genitive plural pitkien, partitive plural pitkiä, adessive singular pitkällä, and adessive plural pitkillä. The adessive suffix -llä/-llä marks location on or with something, and when combined with the plural adjective form, it results in pitkillä. The stem vowel and consonant patterns follow standard Finnish adjective inflection rules.

Usage-wise, pitkäillä occurs in descriptive prose where multiple nouns are involved and the speaker intends to describe their longness or the fact that something is located on or with long items in the adessive sense. It is a normal, grammatical form in written and spoken Finnish, though in everyday speech speakers may opt for shorter or more general constructions depending on context.

See also: Finnish grammar, adjectives, adessive case, -lla/-llä suffix.

References: Finnish Language Institute (Kotus) guidance on adjective inflection and case endings.