1. most ill or unwell (superlative of sick)
2. most disgusted or nauseated (superlative of sick)
3. most excellent or impressive
Usage: slang

Examples

• She was the sickest patient in the hospital ward.
• The smell of rotten eggs made him feel the sickest he’d ever felt.
• That was the sickest skateboard trick I’ve ever seen!
• He looked the sickest after eating all that candy.
• The sickest part of the roller coaster was the loop.
• She felt sickest during the first trimester of pregnancy.
• That guitar solo was absolutely the sickest!