1. superlative form of sincere; most genuine, honest, or heartfelt
Usage: superlative form

Examples

• Please accept my sincerest apologies for the mistake.
• She offered her sincerest condolences to the family.
• His sincerest wish was to help others in need.
• The teacher gave her sincerest praise to the hardworking student.
• With my sincerest gratitude, I thank you for your support.
• He expressed his sincerest regret about the incident.