Pretty much. It helps if you think the word "dinosaur" has two partially overlapping meanings:

1. Cladistic: every single descendant of the last common ancestor between the triceratops and a duck, including both. Plus pretty much any bird.
2. Popular: a bunch of extinct animals like the T-Rex, velociraptor, triceratops, etc. Plus animals visually resembling them, regardless of cladistic classification. Notably, it does not includes Aves aka modern birds.

So for example. Turkeys would fit #1 but not #2. Depending on the person, dimetrodons and pterosaurs would fit #2, but not #1 [see note]. A T-rex would fit both.

NOTE: pterosaurs aren't from the clade Dinosauria, but from a distantly related clade called Pterosauria. Dimetrodons are synapsids so they're closer to us mammals than to Dinosauria.