cansadísimo
exhausted
cansado
tired
+
-ísimo
superlative suffix
Cansadísimo means exhausted and can be thought of as cansado0 (tired0) + -ísimo1 (superlative suffix1), meaning 'extremely tired'.
adjective
- exhaustedExtremely tired or exhaustedDespués de correr el maratón, estaba cansadísimo. // After running the marathon, I was exhausted.