1. most extremely unpleasant, shocking, or terrible (superlative form of ghastly)
Usage: superlative form

Examples

• That was the ghastliest movie I've ever seen.
• The accident scene was the ghastliest sight imaginable.
• She told us the ghastliest story about her camping trip.
• The ghastliest part of the haunted house was the basement.
• His ghastliest nightmare finally came true.
• The weather turned ghastliest just as we started hiking.