arduous /ärˈdū-əs/

1. Steep, difficult to climb
2. Difficult to accomplish
3. Laborious

ardˈuously adverb

• ground game
• ground glass
• groundhog
• Groundhog Day
• groundhogs
• ground-hold
• groundhopper
• groundhoppers
• ground ice
• grounding
• groundings
• ground ivies
• ground ivy
• ground-ivy
• groundless
• groundlessly
• groundlessness
• groundlessnesses
• groundling
• groundlings
• ground loop
• ground loops
• ground mail
• groundman
• groundmass