earnest

earnest adjective uk/ˈɜːnɪst/ us
very serious and sincere

серьезный
an earnest young man an earnest effort in earnest
If something begins to happen in earnest , it really starts to happen in a serious way.

всерьез, по-настоящему
The research will begin in earnest early next year. be in earnest
to be very serious about something and mean what you are saying

говорить совершенно серьезно

earnest ly adverb

серьезно
earnest ness noun [ U ]

серьезность