dilution
noun [ U ]
uk/daɪˈluːʃən/ us/dɪˈluːʃən/the process or action of making something less strong or valuable:
The destroyer of brand integrity is "brand dilution", which is the perverse reward for popularity.
FINANCE
the process or action of making a company's shares less valuable by making more shares available:
The company is working to prevent dilution resulting from stock splits or similar transactions.