different between lacklustre vs slothful

English

lack +? lustre

lacklustre (comparative more lacklustre, superlative most lacklustre)

lacklustre (countable and uncountable, plural lacklustres)

(British) Alternative spelling of lackluster
- 1990, The Nigerian Economist (volume 4, page lxxii)
  Secondly, the fear of offending the military has reduced the campaigns to mere lacklustres. Promises are reeled off with so much obvious lack of passion that it is quite possible the party bosses themselves hardly believe what they say […]

sloth +? -ful

slothful (comparative more slothful, superlative most slothful)

Lazy; idle; tending to sloth.
Synonyms: inactive, sluggish, indolent
Antonyms: active, unslothful
- He also that is slothful in his work is brother to him that is a great waster.

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