infinitesimally       
adverb  formal uk/ˌɪn.fɪ.nɪˈtes.ɪ.mə.li/ us/ˌɪn.fɪ.nəˈtes.ə.mə.li/
 极微地
to an extremely small degree
  infinitesimally small
 His chances of winning are infinitesimally slim.
 Each action contributes infinitesimally to global warming. 每一个行为都在极其细微地加剧全球变暖。 
 See: infinitesimal
 - More examples
 - Mrs Rusham's face relaxed infinitesimally.
 - The vast majority of Americans face an infinitesimally low risk of infection.
 - He paused infinitesimally.