— gruelingly , adv.
/grooh"euh ling, grooh"ling/ , adj.
1. exhausting; very tiring; arduously severe: the grueling Boston marathon.
n.
2. any trying or exhausting procedure or experience.
Also, esp. Brit., gruelling .
[ 1850-55; slang gruel punishment (n.), punish (v.) + -ING 2 , -ING 1 ]