General:
* Sincere: emphasizes genuineness and heartfelt regret.
* Humble: suggests a recognition of fault and willingness to accept responsibility.
* Contrite: implies deep remorse and a feeling of shame.
* Forthcoming: indicates a prompt and willing apology.
* Unreserved: means the apology is complete and without qualification.
Specific:
* Gracious: describes a kind and polite apology.
* Formal: suggests a more official or structured apology.
* Insincere: implies a lack of genuine regret.
* Perfunctory: describes a brief and superficial apology.
Figurative:
* Heartfelt: evokes strong emotional connection.
* Meaningful: emphasizes the significance of the apology.
The best adjective will depend on the specific context and the nature of the apology.