This is the 1163rd most frequent Polish word.
ustalili
"They established" or "they agreed."
This usage of 'ustalili' comes from its verb 'ustalić,' which means 'to agree on' or 'to establish,' indicating a mutual agreement between parties.
Ustaliliśmy termin spotkania na przyszły tydzień.
We agreed on the meeting date for next week.
In this sentence, 'ustalili' means 'determined' as in establishing facts or conclusions after examinations or analysis.
Naukowcy ustalili, że zjawisko jest rzadziej spotykane, niż sądzono.
Scientists determined that the phenomenon is rarer than previously thought.
Here 'ustalili' implies 'decided or finalized,' involving a conclusion reached after deliberation.