This is the 13641st most frequent Russian word.
неискренними
Not sincere.
Here, "неискренними" is used as an adjective describing "words," indicating that they lack sincerity.
Её слова казались неискренними, так как она избегала смотреть мне в глаза.
Her words seemed insincere, as she avoided looking me in the eye.
In this sentence, "неискренними" describes "compliments," suggesting they seem lacking in honesty.
Некоторые люди считают комплименты неискренними, если они звучат слишком натянуто.
Some people consider compliments insincere if they sound too forced.
Here, "неискренними" directly modifies "людьми," emphasizing the people are perceived as insincere in behavior.