1. most unpleasant, dirty, or of poor quality (superlative form of grotty)
Usage: British informal

Examples

• That was the grottiest hotel room I’ve ever stayed in.
• The grottiest part of the city had broken streetlights and litter everywhere.
• She wore her grottiest clothes to clean out the garage.
• The school cafeteria served the grottiest food imaginable.
• After three days of camping, his tent was the grottiest thing in the campground.
• The grottiest bathroom in the building was finally renovated.