
1) Arduous 2) Backbreaking 3) Difficult 4) Effortful 5) French word used in English 6) Grueling 7) Gruelling 8) Hard 9) Heavy 10) Punishing 11) Tedious 12) Toilsome
Found on
https://www.crosswordclues.com/clue/laborious

• (a.) Devoted to labor; diligent; industrious; as, a laborious mechanic. • (a.) Requiring labor, perseverance, or sacrifices; toilsome; tiresome.
Found on
http://thinkexist.com/dictionary/meaning/laborious/
La·bo'ri·ous adjective [ Latin
laboriosus ,fr.
labor labor: confer French
laborieux .]
1. Requiring labor, perseverance, or sacrifices; toilsome; tiresome. « Dost thou love watchings, abstinence, or toil,
Laborious virtues all ? Learn these from Cato.»...
Found on
http://www.encyclo.co.uk/webster/L/2

laborious 1. Characterized by toilsome effort to the point of exhaustion; especially, physical effort. 2. Requiring long, hard work: 'We spent many laborious hours on the project and it is still not completed.' 3. Hard-working; industrious.
Found on
http://www.wordinfo.info/words/index/info/view_unit/1130/3
No exact match found.