1. Lacking brilliance or vitality
   "a dull lacklustre life"
   - lackluster [US], lusterless [N. Amer], lustreless [Brit, Cdn] 
2. Lacking lustre or shine
   "staring with lacklustre eyes"
   - lackluster [US], lusterless [N. Amer], lustreless [Brit, Cdn]

See also: dull, hebetudinous

• heartbreaking
• heartbroken
• heartburn
• heartburning
• hearted
• hearten
• heartening
• heartfelt
• hearth
• hearth money
• hearthrug
• hearthstone
• heartily
• heartiness
• heartland
• heartleaf
• heartleaf arnica
• heartleaf manzanita
• heartless
• heartlessly
• heartlessness
• heartrending
• heartrot
• hearts
• heartsease