staid

/stayed/

Adjective

Sedate, respectable, unadventurous

Something that is staid is dignified, respectable — possibly even boring, like a staid dinner party that is heavy on the important guests but light on the laughs.

Staid is pronounced just like "stayed" — in fact, it comes from stay, meaning "fixed" or "permanent." Something that is staid is sedate, slightly dull, and tends to stay the same. Whether it’s a middle-class lifestyle, a conservative law firm, your unadventurous aunt, or an old navy plaid sofa, the word staid can be used to describe anything that maintains a respectable self-restraint and takes no chances.

(explanation from vocabulary.com)