Eventful means full of things happening. An eventful day, an eventful journey, rather eventful.
It is neutral by definition and negative by tone: an eventful journey is one where things went wrong, and everybody hears that. Uneventful, its opposite, is what anybody wants a flight or an operation to be.
1adjectiveeventfulFull of things happening.
“It was an eventful day: we missed the train, found a puppy and got engaged.”
eventful is a quality.
Event plus -ful, from Latin eventus, an outcome, from evenire, to come out.
Proto-Indo-European
*gʷem-
Latin
ēventus — an event, occurrence
Middle French
event
English
event
English, today
eventful
Built from
From event + -ful. event comes from Middle French event, from Latin ēventus (“an event, occurrence”), from ēveniō (“to happen, to fall out, to come out”), from ē (“out of, from”), short form of ex + veniō (“come”); related to venture, advent, convent, invent, convene, evene, etc.
Etymology from Wiktionary, CC BY-SA