v.1. To improve someone or something in appearance or stylishness: You can smarten up a dull sweater with a fashionable pin. The designer took my original idea for the greeting card and smartened it up.
2. To improve someone's appearance or stylishness: I think this colorful new hat will smarten you up! Please try to smarten yourself up before we get to the party.
3. To improve in appearance or stylishness: I had to smarten up when I moved to the city, so I bought a new suit.
4. To make someone more aware, informed, or sophisticated: I had to smarten up my young cousins about money management. The experiences they had when buying their first home smartened them up.
5. To become more aware, informed, or sophisticated: We smartened up after we had been scammed by the salesperson, and never went back to that store again.