Regret is a feeling of sadness, repentance, or disappointment over something that has happened or been done, especially a loss or missed opportunity.
Common expressions with regret:
1. "I regret to inform you..." (formal expression of bad news)
2. "No regrets" (expression of satisfaction with one's choices)
3. "Live without regret" (philosophical advice)
Grammatical forms: verb (regret/regretted/regretting), noun (regret/regrets)