insincerely

/ˌɪnsɪnˈsɪrli/
adverb
  1. In a way that is not honest or genuine; pretending to feel or believe something that one does not.
    • The politician thanked the crowd insincerely, rushing off before anyone could ask questions.
    • He apologized insincerely, just to avoid getting in trouble.
    • She smiled insincerely at her rival during the award ceremony.
Antonyms