This is the 13676th most frequent Russian word.
необоснованы
Unfounded or baseless.
In this sentence, "необоснованы" is used as an adjective describing the complaints, indicating that they lack a valid basis.
Его жалобы на качество обслуживания были необоснованы.
His complaints about the quality of service were unfounded.
Here, "необоснованы" serves as a predicate to describe the arguments, pointing out their lack of support or justification.
Некоторые из представленных аргументов оказались необоснованы.
Some of the presented arguments turned out to be unsubstantiated.
In this case, "необоснованы" modifies the accusations to specify that they were without merit or evidence.