Pronunciation: (är'jOO-us or, esp. Brit., är'dyOO-), [key]
1. requiring great exertion; laborious; difficult: an arduous undertaking.
2. requiring or using much energy and vigor; strenuous: making an arduous effort.
3. hard to climb; steep: an arduous path up the hill.
4. hard to endure; full of hardships; severe: an arduous winter.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.