- requiring great exertion; laborious; difficult: an arduous undertaking.
- requiring or using much energy and vigor; strenuous: making an arduous effort.
- hard to climb; steep: an arduous path up the hill.
- hard to endure; full of hardships; severe: an arduous winter.
- requiring great physical or mental effort; difficult to accomplish; strenuous
- hard to endure; harsharduous conditions
- hard to overcome or surmount; steep or difficultan arduous track
1530s, “hard to accomplish, difficult to do,” from Latin arduus “high, steep,” also figuratively, “difficult,” from PIE root *eredh- “to grow, high” (see ). Literal sense of “high, steep, difficult to climb,” attested in English from 1709.