1. rapid increase in numbers or amount; multiplication
2. the spread or development of something, especially something undesirable

Examples

• The proliferation of smartphones has changed how we communicate.
• Nuclear proliferation remains a major global concern.
• The proliferation of weeds in the garden required immediate attention.
• Social media has led to the proliferation of fake news.
• The proliferation of fast-food restaurants has contributed to obesity rates.
• Scientists are studying the proliferation of cancer cells.
• The proliferation of online courses has made education more accessible.