arduous /ärˈdū-əs/

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

ardˈuously adverb

• indefensible
• indefensibleness
• indefensibly
• indefinable
• indefinableness
• indefinablenesses
• indefinably
• indefinite
• indefinitely
• indefiniteness
• indefinitenesses
• indehiscence
• indehiscences
• indehiscent
• indelibilities
• indelibility
• indelible
• indelibleness
• indeliblenesses
• indelibly
• indelicacies
• indelicacy
• indelicate
• indelicately
• in deliciis