A person who presides over a meeting or assembly, often referred to as a temporary speaker until a permanent one is chosen.

अस्थायी अध्यक्ष

English Usage: The protem speaker opened the meeting with a few words of welcome.

Hindi Usage: अस्थायी अध्यक्ष ने बैठक की शुरुआत कुछ स्वागत शब्दों से की।