Slack
Slack adjective - Failing to give proper care and attention.
Uncheerful and slack are semantically related In some cases you can use "Uncheerful" instead an adjective "Slack".
Uncheerful
Uncheerful adjective - Causing sad feelings of gloom and inadequacy.
Slack and uncheerful are semantically related in not in the mood topic. Sometimes you can use "Slack" instead an adjective "Uncheerful".
Mutual synonyms
Cite this Source
Uncheerful and Slack. (2016). Retrieved 2026, August 02, from https://thesaurus.plus/related/slack/uncheerful
Slack & Uncheerful. N.p., 2016. Web. 02 Aug. 2026. <https://thesaurus.plus/related/slack/uncheerful>.
Uncheerful or Slack. 2016. Accessed August 02, 2026. https://thesaurus.plus/related/slack/uncheerful.
Google Ngram Viewer shows how "slack" and "uncheerful" have occurred on timeline