an opportunist lier.
glib
There is no way to tell. A psychopathic killer can be very clever at sounding very loving and sincere, for example.
lies
more sincere (sincerer), the most sincere (sincerest)
A sincere person is always respected for his sincerity. This is the sincere approach to make a sentence with the word 'sincere'.he was sincere in his efforts to please
The superlative degree of word sincere can be most sincere ,or sincerest according to its use in the sentence.
clever = klug clever =schlau clever = gescheit clever = clever
The noun forms for the adjective sincere are sincereness and sincerity.
The comparative form of "sincere" is "more sincere," while the superlative form is "most sincere." For example, you might say, "She is more sincere than her friend," and "He is the most sincere person I know." Unlike some adjectives, "sincere" does not form its comparative and superlative by simply adding "-er" or "-est."
"With sincere appreciation" is the correct phrase. It indicates that the appreciation is accompanied by sincerity.
Antonyms for sincere include:deceitfuldishonestdisingenuousinsincerelyingtrickytwo-faceduntrustworthy
I gave a sincere apology to my mother.