arduous /ärˈdū-əs/

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

ardˈuously adverb

• flint glass
• flint glasses
• flint-heart
• flint-hearted
• flintier
• flintiest
• flintified
• flintifies
• flintify
• flintifying
• flintily
• flintiness
• flintinesses
• flint-knapper
• flint-knappers
• flint-knapping
• flintlock
• flintlocks
• flints
• flinty
• flip
• flip chart
• flip charts
• flip-dog
• flip-dogs