Eventlessly is a derived term of eventless.
As an adverb eventlessly
is without any major event; uneventfully.
As an adjective eventless is
without events; uneventful.
Other Comparisons: What's the difference?
Without any major event; uneventfully.
* 1870 , Lucius O'Brien Blake, Rich and Rare (page 189)
- The few next days passed eventlessly by, or at least as eventlessly as days can pass to visitors in Home.
Without events; uneventful.
* (Roger Ebert)
- Life on board the Discovery is presented as a long, eventless routine of exercise, maintenance checks, and chess games with HAL.