"Your sun has failed freshman English. I'm afraid he'll have to attend summer school," Tom's teacher said with a mirthless smile.
Source: tatoeba (10763873)
Ranked by relevance and common usage.
Keep "mirthless" when the sentence already sounds natural, when a synonym would add unintended emphasis, or when readers need the most familiar wording. A synonym should clarify or sharpen the message, not simply make the sentence look more varied.
If two options seem close, choose the one that best matches the audience and purpose of the sentence.
Choose a synonym only if it keeps the core idea of "mirthless" intact in the sentence you are editing.
Check whether the replacement sounds more formal, casual, emotional, technical, or forceful than the original word.
Read the full sentence after the swap. Keep the synonym only when the sentence becomes clearer or more precise.
Review note: Synonym lists are ranked with lexical data and reviewed for practical writing value. Use the comparison notes, sentence evidence, and source labels together; a high-ranking synonym can still be wrong when the audience, register, or grammar changes.
After choosing a replacement for "mirthless", read the sentence once for meaning and once for rhythm. The best synonym should feel natural in the full sentence, not only accurate in a word list.
If the synonym makes the sentence slower, vaguer, or more dramatic than intended, keep "mirthless" or choose a simpler alternative from the closest-match group.
OpenGloss and ConceptNet supply richer edges like generalizations, collocations, and derivations.
4 total sentences available.
"Your sun has failed freshman English. I'm afraid he'll have to attend summer school," Tom's teacher said with a mirthless smile.
Source: tatoeba (10763873)
The land itself was a desolation, lifeless, without movement, so lone and cold that the spirit of it was not even that of sadness. There was a hint in it of laughter, but of a laughter more terrible than any sadness—a laughter that was mirthless as the smile of the sphinx, a laughter cold as the frost and partaking of the grimness of infallibility.
Source: tatoeba (12169496)
The laughter of man is more terrible than his tears, and takes more forms: hollow, heartless, mirthless, maniacal...
Source: wiktionary
In life, David Lodge was surprisingly mirthless. Luckily, his wife was a hoot [title]
Source: wiktionary
Closest matches include cheerless, discontented, dour, gloomy, grim.
Compare the replacement against real sentence context. This entry includes sample sentences so you can check tone, grammar, and meaning before swapping words.