arduous Synonyms

laborious hard strenuous exhausting backbreaking gruelling grueling wearisome heavy straining operose demanding trying onerous toilsome burdensome punishing painful fatiguing difficult ticklish testing stressful strung throbbing thorny taxing sore rigorous rugged sanguineous serious severe sheer shingly sideling sisyphean slaughterous rough steep problematic tight unenviable unaffecting labor-intensive laboured bone dry brain surgery nerve-wracking unbearable