1. most serious, steady, and avoiding excitement or fun (superlative form of staid)
Usage: formal

Examples

• She was the staidest member of the conservative board.
• Even the staidest professor couldn’t help but smile at the joke.
• The staidest neighborhoods often have the strictest rules.
• He chose the staidest outfit for the formal dinner.
• Among all her siblings, she was considered the staidest.
• The staidest customers preferred the traditional menu items.