weighty
adj.adj. describing something that is very heavy or has a lot of importance. You use this to talk about books that are thick and hard to carry, or ideas that are serious and important.
adj. characterised by great mass or significant importance. Often used to describe physical objects with substantial weight or abstract concepts with considerable influence.
The old book is very weighty and hard to lift.
The professor's latest paper is a weighty contribution to the field of economics.
The treaty was a weighty document, its pages filled with the legal intricacies of a peace that would define the century.
From Middle English weighti, weghti, wighti, equivalent to weight + -y. Cognate with Scots weichty, wechty, wichty, Saterland Frisian wichtich, West Frisian wichtich, Dutch wichtig, gewichtig, German wichtig, Danish vigtig, Swedish viktig. Compare typologically Russian ве́ский (véskij), весо́мый (vesómyj) (< вес (ves)). Also compare the same meaning development from cognate (by borrowing) Polish waga (< ... < Proto-Germanic *wēgō): ważny (whence Russian ва́жный (vážnyj)).