1. A source of harm or ruin: Uncritical trust is my nemesis.
2. Retributive justice in its execution or outcome: To follow the proposed course of action is to invite nemesis.
3. An opponent that cannot be beaten or overcome.
4. One that inflicts retribution or vengeance.
5. Nemesis Greek Mythology The goddess of retributive justice or vengeance.
6. Rof Stick Insect