some words are "allowed" to have a suffix
 but others are not
  bigger - smaller
  but "more fun" rather than "funner"
  and "more boring" rather than "boringer"
  and "more patient" rather than "patienter"
  and "more expensive" rather than "expensiver"
   but cheap - cheaper

tasty - tastier
dry - drier
 and clothes dry in a "dryer" to become "drier"