gruellinggru‧el‧ling British English, grueling American English /ˈɡruːəlɪŋ/ adjective 
Word Origin
The cast took a break from their gruelling schedule. a grueling journey► see thesaurus at tiring
Word OriginWORD ORIGINgrueling
ExamplesOrigin:
1800-1900 gruel ‘to punish’ (1800-1900), from gruel ‘food’; because people were given gruel as a punishmentEXAMPLES FROM OTHER DICTIONARIES
Thesaurus- The Le Mans 24 hour race is the most gruelling event in the motor-racing calendar.
- A chance for a last flourish and a bit of fun at the end of a gruelling league campaign.
- Events include Hang Tough - a gruelling game of aerial chess - and Atlaspheres, a battle fought in giant globes.
- He has a serious nature and his powers of concentration are a boon when it comes to his gruelling training schedule.
- In his gruelling work schedule, sixty-year old Garrett continues at a rate that would tax many men half his age.
- It could take fourteen weeks to complete the gruelling journey on foot from London to Rome in the Middle Ages.
- McAllister should be on his knees after a gruelling month at Elland Road.
- Middlesbrough face a gruelling ten-match programme in April.
- Or see them through an abortion, a divorce, a gruelling court-case?
THESAURUS► tiring
very difficult and tiring: making you feel that you want to sleep or rest: · The journey was really tiring.· I’ve had such a tiring day.· It was tiring work.
► exhausting extremely tiring: · I had to drive nine hours without a break – it was exhausting.· an exhausting week of singing, acting, and dancing
► hard very tiring and difficult – used about days, journeys etc: · a hard day at work· The last part of the journey was very hard.
► wearing tiring because you have to use a lot of your mental energy, and often become bored – used about people, situations etc: · I find her constant questions rather wearing.· Kids of that age can be very wearing.· His films always tend to have the same plots, which does get rather wearing after a while.
► gruelling British English, grueling American English (also punishing) very tiring physically or mentally – used when you have to keep doing something for a long time: · a gruelling journey across the desert· a gruelling race· a punishing schedule· a punishing exercise regime
► backbreaking backbreaking work is extremely tiring and needs a lot of physical effort: · Clearing the land was slow backbreaking work.· Laborers were paid $2 a day for backbreaking farm work.
► something is a killer informal used when saying that something is extremely tiring: · Today was a real killer.
► fatiguing formal making you feel very tired: · Factory work was repetitive and fatiguing.
Longman Language Activatorneeding a lot of energy or physical effort► hard tiring and needing a lot of work, energy, or physical effort: · Let your mother sit down. She's had a hard day at work.· Their car broke down, and they were suddenly faced with a long hard walk back to the nearest town.
► strenuous needing a lot of physical effort: · The doctors advised against any strenuous activity for six weeks.· Last season his trainers put him through a strenuous running program.
► backbreaking/back-breaking backbreaking work, especially work that involves carrying and lifting heavy things, is extremely hard and needs a lot of physical effort: · After four hours of backbreaking work, we had finally pulled the wall down.
► gruelling British /grueling American something that is gruelling is extremely tiring because it continues for a long time and you have to use a lot of effort continuously: · The Le Mans 24-hour race is the most gruelling event in the motor-racing calendar.· Before they join the army, young recruits are put through a particularly grueling endurance course.
► arduous written work or a journey that is arduous is long and tiring and needs a lot of strength and effort: · In those days, long-distance travel was slow and arduous.· Today, Corbett will continue his arduous climb to the top of the park's highest peak.
► punishing extremely difficult in a way that damages or weakens something or makes someone feel very tired: · The transatlantic flight was a punishing task for the plane's old engines.· He set himself a punishing schedule of talks, lectures and conferences all over America.
► be murder spoken use this when something is extremely difficult and needs a lot of effort or skill: · Traveling five days a week is murder. I can't do it anymore.it is murder doing something: · It's murder trying to park in this town!
► be a slog British informal if something is a slog, it takes a lot of time and effort and is often boring: · He didn't become famous overnight -- it's been a long hard slog.· The first half of the book was quite interesting but the last part was a bit of a slog.
The cast took a break from their gruelling schedule. a grueling journey► see thesaurus at tiring