n.
Variant: or gru · el · ling
Pronunciation: ' grü- ə -li ŋ
Function: adjective
Etymology: from present participle of obsolete gruel to exhaust, punish, from gruel, noun
Date: 1852
: trying or taxing to the point of exhaustion : PUNISHING <a grueling race>
– gru · el · ing · ly \ -li ŋ -l ē \ adverb