A prefix is an added beginning to a word, which often changes its meaning.
If you add the prefix "mis" to spelled, you get the word "misspelled", which means spelled incorrectly. This is, indeed, the antonym, or opposite, of spelled.
disable, unable, and enable
in-
The prefix 'im' can added to make the word impolite.
"Possibility" doesn't have a prefix. You could add the prefix im- to it to make the word impossibility.
asymmetricantisymmetric
pre
The adding a prefix to the word "add" would result in the word "postadd".
in-
In the word "inform", in- is a prefix. You could add the prefix mis- to it to get misinform.
If you add a prefix to a word, you can change the meaning.
Oper is the prefix. There is no suffix. Able is the root word.
You could add the prefix mis- to it to make the word misfits.
The prefix 'im' can added to make the word impolite.
The prefix in "unpalatable" is "un-" and the suffix is "-able".
"Possibility" doesn't have a prefix. You could add the prefix im- to it to make the word impossibility.
Pre-The prefix for prefix is pre; because it's before the root word fix.
un-
Misspelled