Find another word for unhappy. Understand sad meaning and enrich your vocabulary 68 synonyms of unhappy from the Merriam-Webster Thesaurus, plus 93 related words, definitions, and antonyms. All Free. Sad definition, affected by unhappiness or grief; sorrowful or mournful: to feel sad because a close friend has moved away. sad synonyms and antonyms in the English synonyms dictionary, see also 'sadden',saddle',shade',shady', definition. sad - WordReference thesaurus: synonyms, discussion and more. Another word for happy: pleased, delighted, content, contented, thrilled | Collins English Thesaurus See more.