1. lacking brightness, shine, or luster; dull in appearance
2. lacking energy, enthusiasm, or interest; uninspired or mediocre

Examples

• The old painting had a lacklustre finish after years of dust accumulation.
• His lacklustre performance in the game disappointed the fans.
• The company's sales were lacklustre this quarter compared to last year.
• She gave a lacklustre presentation that failed to engage the audience.
• The metal lost its shine and became lacklustre over time.
• Despite high expectations, the movie received lacklustre reviews from critics.
• His eyes looked lacklustre and tired after the long journey.