arduous /ärˈdū-əs/

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

ardˈuously adverb

• hart of grease
• harts
• hartshorn
• hartshorns
• hart's tongue
• harum-scarum
• harum-scarums
• haruspex
• haruspical
• haruspicate
• haruspicated
• haruspicates
• haruspicating
• haruspication
• haruspications
• haruspices
• haruspicies
• haruspicy
• Harvard classification
• harvest
• harvest bug
• harvest bugs
• harvested
• harvester
• harvesters