arduous /ärˈdū-əs/

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

ardˈuously adverb

• phyllotaxes
• phyllotaxis
• phyllotaxy
• Phyllotria
• phylloxera
• phylloxeras
• phylogeneses
• phylogenesis
• phylogenetic
• phylogenetically
• phylogenetics
• phylogenies
• phylogeny
• phylum
• phys
• physalia
• physalias
• physalis
• physalises
• physeter
• physeters
• physharmonica
• physharmonicas
• physi-
• physiatrics