Something that's strident is loud, grating, and obnoxious. Your roommate's strident laughter as he watches cartoons late into the night might inspire you to buy a pair of ear plugs.
Strident is related to the Latin word strix , meaning "screech owl." This is a kind of owl that doesn't hoot. It screeches in a strident way. Strident can also describe the forceful expression of an unpopular opinion. Don't confuse strident with striding, which means walking quickly with a wide step. If you're angry at your brother, you might come striding into his room and begin making a strident case for why he has done you wrong.