The definition for diffident is "Lacking self–confidence." Used in a sentence: The diffident student never raised her hand in class, even when she knew the answer.

The definition for frugal is "Thrifty, cheap." Used in a sentence: The frugal shopper only bought items that were on sale.

The definition for genial is "Sympathetic, friendly." Used in a sentence: The genial host warmly greeted his many guests.

The definition for opportune is "Suitable or convenient." Used in a sentence: Quan stepped onto the platform at the most opportune time, just as the train pulled in.

The definition for turmoil is "Extreme confusion, agitation." Used in a sentence: The windstorm caused such turmoil in the lake that the sailboat capsized.