The true opposite of prefix is no prefix.
But, as a prefix means something added at the start of a word. the generally understood opposite is suffix - which is something added to the end of a word.
Ob - toward/face to face
Pon/posit - put, place
Hypo is the opposite of the prefix hyper.
The prefix in the word upgrade is 'up'. The opposite would be downgrade.
The prefix un- makes the word "unsuitable."
The opposite is impatient.
The prefix 'dis' means not or the opposite of something.
Hypo is the opposite of the prefix hyper.
The opposite prefix of the prefix "meta-" is "pre-".
The prefix for "counteract" is "counter-".
The prefix in the word upgrade is 'up'. The opposite would be downgrade.
The prefix un- makes the word "unsuitable."
Yes, unlike does have that prefix. The prefix is un-.
Rational is the opposite of irrational. The ir- prefix is a variation of the in- prefix and means "not".
The opposite form of 'expendable' with a prefix added is 'inexpendable.'
The opposite is impatient.
The opposite of active using a prefix is "inactive."
The prefix "dif means the opposite of, or reverse.
The prefix 'dis' means not or the opposite of something.