1. extremely difficult, severe, or intense
Usage: informal
2. remarkably impressive or extreme in degree
Usage: informal

Examples

• The storm brought hellacious winds that knocked down power lines.
• She faced a hellacious workload during finals week.
• The mountain trail was hellacious, with steep climbs and loose rocks.
• Traffic was hellacious during the holiday weekend.
• He threw a hellacious fastball that the batter couldn’t touch.
• The heat wave created hellacious conditions for the marathon runners.