kiireisillä
Kiireisillä is a Finnish grammatical form that functions as an adjective-based noun referring to a group of people characterized by being busy. It is the adessive plural form of the adjective kiireinen, and it can be used to mean “the busy ones” or “the busy people.” In this sense, kiirea is not a separate lexical item but a specific inflected form of an adjective used pronominally to denote a group.
Kiireisillä is formed from kiireinen with the plural adessive suffix -illä. The adessive case marks the referent
Nuances and relation to other forms
Kiireisillä emphasizes the state or condition of the group (being busy) and can carry a evaluative nuance,
Kiireinen, kiireiset ihmiset, Finnish grammar, adessive case.