1. with the head leading; head first
2. in a rush; without thinking or planning carefully

1. done without careful thought; rash or hasty

Examples

• She dove headlong into the swimming pool.
• He fell headlong down the stairs.
• The company rushed headlong into the new market without proper research.
• They made a headlong dash for the exit when the alarm sounded.
• Her headlong pursuit of fame led to many mistakes.
• The cyclist went headlong over the handlebars.
• Don’t make such headlong decisions about your career.