1. superlative form of ill: most sick or unwell
Usage: formal
2. most excellent, impressive, or skillful
Usage: slang; informal

Examples

• She was the illest patient in the entire hospital ward.
• Among all the competitors, he felt the illest before the race.
• That was the illest performance I’ve ever seen on stage.
• She’s got the illest dance moves in the whole crew.
• His freestyle rap was the illest thing at the battle.
• The illest part of the concert was when they played their hit song.