LABORIOUS
Meaning of LABORIOUS in English
adjective
Synonyms: hard 6, arduous, difficult, effortful, heavy, labored, operose, strenuous, toilsome, uphill
Antonyms: easy, effortless
Merriam Webster.
Collegiate thesaurus English vocabulary.
Английский энциклопедический словарь тезаурус.
2003