Single-handed means doing something completely by yourself, without help from anyone else. When a sailor crosses the ocean single-handed, she manages every aspect of the voyage alone: navigating, adjusting the sails, cooking meals, and staying alert through storms. When you finish a difficult project single-handedly, you deserve full credit because you accomplished it through your own effort and skill.

The word emphasizes independence and self-reliance. A student who single-handedly organizes a school fundraiser handles all the planning, communication, and execution without a team. It's different from just working alone on homework: single-handed suggests tackling something challenging that people normally do together.

You might also hear single-handedly, which means the same thing. Someone who single-handedly wins a game for their team makes the difference through their own exceptional performance.