If you describe something such as an issue or a decision as weighty, you mean that it is serious or important. Surely such weighty matters merit a higher level of debate? = serious, important
having relatively great weight; heavy; "a weighty load"; "a weighty package" weighing heavily on the spirit; causing anxiety or worry; "weighty problems
You use weighty to describe something, especially a book, that is heavy or heavier than you would expect. Simon lifted a weighty volume from the shelf. = hefty
To describe a wine with plenty of power and fruit that takes time in the mouth to get the full benefit from This term can apply to red wines as well as white
of great gravity or crucial import; requiring serious thought; "grave responsibilities"; "faced a grave decision in a time of crisis"; "a grievous fault"; "heavy matters of state"; "the weighty matters to be discussed at the peace conference"