The phrase suggests frustration or annoyance when something repetitive loses its effect or appeal. Her daily complaints about work have started to wear thin.
Pro Tip 2/3
Metaphorical Use
Often used metaphorically to describe non-physical processes like patience. After the long delay, the audience's patience was wearing thin.
Pro Tip 3/3
Overuse Effect
Use it to describe something that becomes less enjoyable or convincing when repeated too often. The charm of his storytelling is wearing thin with every retelling.